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¿Cuántas de las ecuaciones indicadas a continuación representan la

línea que pasa por los puntos (2,3) y (4, -- 7)?
5x + y = 13
y + 7 = –5(x – 4)
y = –5x + 13
y –7 = 5(x – 4)

1 Answer

4 votes

Answer: 5x + y = 13 / y = -5x + 13

Explanation:

If you want to know if these points are in a equation, you have to check each point in each equation.

So.. let's try. We have the first point (2,3). Now, we're checking in the first equation:

5 . (2) + (3) = 13 (this is a true sentence)

Let's try the another point (4, -7)

5.(4) + (-7) = 13 (this is a true sentence as well)

the second one: y + 7 = -5(x + 4)

3 + 7 = -5(2+6) (it isn't true. So, I won't try the another point).

the third one: y = -5x + 13

(3) = -5.(2) + 13 (this is a true sentence. Let's check now the another point).

(-7) = -5(4) + 13 (this is a true sentence as well).

the fourth one: y - 7 = 5(x + 4)

(3) - 7 = 5(2 + 4) (it isn't true. I won't check the another point).

Finally, we have as a answer the first and the third equations.

User Martin Gergov
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