Shadowing Practice: Relations and Functions | Algebra - Learn English Speaking with Video

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in this video we're going to focus on relations and functions
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so what is a relation a relation is a set of pairs of input
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and output values here
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we have three ordered pairs in the first relation on the
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left the x value is the input value the y value
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is the output value the x values is associated with the
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domain of the relation the y values is associated with the range of the relation
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so now let's focus on part a list the domain
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and range of each relation so let's start with the domain
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so what we're gonna do is we're gonna make a list of all of the x values
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and I'm going to write it in ascendant order.
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So first we have negative 3 and then 0 and 2.
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Now let's write the range of that relation.
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So we're going to focus on the y values and it's already listed in ascendant order.
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So 1, 4, and 5.
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Now, let's do the same thing for the other relation.
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So, let's write out the domain.
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So, the lowest x value is negative 2.
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Next is 1 and then 3.
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Now, let's write out the range of that relation.
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The lowest y value is negative 2.
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And then it's 3, 4, and 7.
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So that's how you can write out the domain and range of each relation.
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Now how can we determine if the relation is a function?
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In order for the relation to be a function, every input value must have only one output value.
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If an input value corresponds to two or more output values, that relation is not a function.
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Now, let's focus on the first relation.
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So we have the ordered pair 2 -1.
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The input value is 2, the output value is 1.
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And then negative 3, 4.
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So negative 3 corresponds to 4, and then 0 corresponds to 5.
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So for the first relation, we can see that for every input value, there's only one output value.
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Now let's focus on the second relation.
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So we have the ordered pair 1, 3.
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Next is negative 2, 4.
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And then it's 3, negative 2.
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And then finally, negative 2, 7.
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So for the second relation, notice that negative 2 corresponds to two different output values.
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Now that's a problem.
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If you put in an input value of negative 2, should the output be 4 or 7?
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So whenever you have that situation, you know that relation is not a function.
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The first one is a function.
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Every input value corresponds to an output value, just one output value.
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So a quick way to look at a relation to see if it's not going to be a function, look for repeated x values.
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If you see two x values that are the same but correspond to two different y values, then you know the relation is not a function.
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It's a very simple website, not too complicated,
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but for those of you who want to be notified anytime I release specialized content in the form of a video,
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an ebook, an article.
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It could be a digital course or a podcast.
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If you want to be notified, feel free to join the email list.
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And once you confirm your email, you're going to get access to a page that has all of my playlists listed on it.
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And this includes my final exam videos and also my test prep videos.
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So feel free to join the email list when you get a chance.
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And let's get back to the video.
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Now let's move on to the next example.
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Draw a mapping diagram of each relation shown below.
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So let's start with the relation on the left.
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We're going to map out the domain and the range.
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So for the domain, we have the values negative 2, 1, and 3.
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For the range, we have the y values, negative 6, 0, and 4.
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Now, negative two corresponds to zero,
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one corresponds to four, three corresponds to negative six.
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So for every input value on the domain side, there's one corresponding output value on to range aside.
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So this is a relation.
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I mean this relation is a function.
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So the answer is yes for the first relation.
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Now let's move on to the second relation.
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So let's create a map and diagram as well.
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So let's start with the domain
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The lowest x value is negative 2
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Next we have 0
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And then the last one is 3
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Now looking at the y values
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The lowest one is negative 1, and then it's going to be 1, 2, and 5.
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So negative 2 corresponds to positive 1.
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0 corresponds to 5.
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3 corresponds to 2.
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and 0 corresponds to negative 1.
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So just by seeing the repeat x values that we see here, we could tell that this is not going to be a function.
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The two x values have two different y values.
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You can see 0 points to negative 1 and 5.
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So the second relation is not a function.
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Now for this one, what we're going to do is we're going to draw a function table of the relation.
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And then we're going to determine if the relation is a function.
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So in this table, we're going to list the input values next to the output values.
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The input values represent the x values.
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The output values represent the y values.
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so the input values it corresponds to the domain and the output values corresponds to the range
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so the lowest input value that we have is negative three next is one and then we have another one
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and then after that is it's three and five
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Now, for this function table, I'm going to write the input value twice, because that's what we have here.
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When writing out the domain and the range, for repeat values, we would write repeat values once.
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Now, negative 3 corresponds to 2.
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For the table, these numbers need to match, so I'm not going to list the output values in ascending order.
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Now, for this one, we could use either one.
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So, I'm going to use 1, 2 for the next one, and then 1, 4.
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Now, when x is 3, y is 7.
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And when x is 5, y is negative 4.
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So, that's the function table and because we have two identical x values that correspond to two different y values,
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we know that this relation is not a function.
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So that's it for this problem.
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When you have a graph, the best way to determine if the graph represents a function is to use the vertical line test.
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And that's what we're going to do in this problem.
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So any way you draw a vertical line for the first graph, notice that the line only touches the graph at one point.
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Therefore, the answer is yes, it represents a function.
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For the next one on the right, if we draw a vertical line, notice at this point, or placing a line at that location,
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we have three points of intersection between the graph and the vertical line.
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If we can get two or more points on a vertical line, then the relation is not a function.
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So we're going to say no. Now, if we put the vertical line here, notice that we have five points on that line.
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So this relation is not a function.
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For the next relation, it doesn't matter where we put the graph.
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We will only get, I mean, it doesn't matter where we put the vertical line we're only going to get one point.
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If we put it here, it's only going to touch the line once.
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So we can't draw a vertical line where it touches two points.
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Therefore, this relation represents a function.
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For the circle, if we put the line here, we can get two points of intersection.
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so we're going to say yes i mean no not yes
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this is no the circle does not represent a function
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it does not pass the vertical line test
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it touches the line at two points in order for it
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to pass the vertical line test the graph must touch the line only at one point
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as we saw in these two cases.
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So that's how you can use the vertical line test to determine if a relation represented by a graph is a function.

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Vocabulario y notas de pronunciación para esta lección

Esta lección de conversación se basa en el vídeo “Relations and Functions”. Las palabras que más se repiten: value, relation, function, negative, correspond. Este vídeo tiene 124 frases y 1357 palabras para practicar shadowing. La parte hablada dura 12:25. El hablante habla despacio, unas 109 palabras por minuto, así que hay tiempo para imitar cada sonido. El 83 % de las palabras está entre las 3.000 más comunes del inglés; conviene repasar el resto antes de empezar.

Vocabulario clave de este vídeo

15 palabras del vídeo que vale la pena aprender, con su pronunciación y significado:

PalabraPronunciaciónSignificado
relation sustantivo/ɹɪˈleɪʃ(ə)n/relación
correspond verbo/ˌkoɹəˈspɑnd/corresponder, equivaler
output sustantivo/ˈaʊtpʊt/producción, output
input sustantivo/ˈɪnpʊt/aportación, aporte
domain sustantivo/ˌdəʊˈmeɪ̯n/dominio
vertical adjetivo/ˈvɝ.tɪ.kəl/vertical
graph sustantivo/ɡɹæf/gráfico, gráfica
associate sustantivo/əˈsoʊʃi.ət/asociado
intersection sustantivo/ˈɪntəɹˌsɛkʃən/cruce
diagram sustantivo/ˈdaɪ.ə.ɡɹæm/diagrama
notify verbo/ˈnoʊtɪfaɪ/notificar
complicated adjetivo/ˈkɑm.plɪˌkeɪ.tɪd/complicado
confirm verbo/kənˈfɝm/confirmar
examination sustantivo/ɪɡˌzæm.ɪˈneɪ.ʃən/examen, examinación
identical adjetivo/ɪˈdɛntɪkl̩/idéntico, clónico

Phrasal verbs que vas a escuchar

PalabraSignificado
get back to verboresponder / contestar (en un rato), volver / tornar a contactar

Pronunciación a tener en cuenta

El hablante usa 23 contracciones y formas reducidas, como we're, I'm, doesn't. Dilas en su forma corta, tal como las oyes.

  • Los sonidos de “sh” y “zh”: relation /ɹɪˈleɪʃ(ə)n/, associate /əˈsoʊʃi.ət/, intersection /ˈɪntəɹˌsɛkʃən/, examination /ɪɡˌzæm.ɪˈneɪ.ʃən/, preposition /ˌpɹɛpəˈzɪʃən/
  • Palabras largas — cuida el acento: associate /əˈsoʊʃi.ət/, intersection /ˈɪntəɹˌsɛkʃən/, complicated /ˈkɑm.plɪˌkeɪ.tɪd/, examination /ɪɡˌzæm.ɪˈneɪ.ʃən/, preposition /ˌpɹɛpəˈzɪʃən/

Sonidos difíciles para hispanohablantes:

  • /z/ — sonora, no /s/: examination /ɪɡˌzæm.ɪˈneɪ.ʃən/, preposition /ˌpɹɛpəˈzɪʃən/, specialize /ˈspɛʃəˌlaɪz/

Cómo practicar con este vídeo

  1. Escucha el vídeo entero una vez sin hablar y anota las palabras que no conoces.
  2. Haz shadowing frase por frase a velocidad normal, repitiendo cada una hasta que tu ritmo coincida con el del hablante.
  3. Grábate y compara con el original, prestando atención a palabras como relation, correspond, output.

¿Qué es la Técnica de Shadowing?

Shadowing es una técnica de aprendizaje de idiomas respaldada por la ciencia, desarrollada originalmente para la formación de intérpretes profesionales y popularizada por el políglota Dr. Alexander Arguelles. El método es simple pero poderoso: escuchas audio en inglés nativo y lo repites en voz alta de inmediato, como una sombra que sigue al hablante con solo 1-2 segundos de retraso. A diferencia de la escucha pasiva o los ejercicios de gramática, el shadowing obliga a tu cerebro y músculos de la boca a procesar y reproducir simultáneamente patrones de habla reales. Las investigaciones muestran que mejora significativamente la precisión de la pronunciación, la entonación, el ritmo, el habla conectada, la comprensión auditiva y la fluidez al hablar, convirtiéndola en una de las metodologías más efectivas para la preparación del IELTS Speaking y la comunicación en inglés en el mundo real.

Técnica de shadowing: lee la guía completa paso a paso →