Question

Y varies inversely to x. If y= 7 when x= -4, what is y when x=5?

Answer 1

Answer:

$y = - 5 \frac{3}{5}$

Step-by-step explanation:

$y = \frac{k}{x}$, where k is a constant. (Since y varies inversely to x)

Let's find the value of k first.

when y=7, x= -4,

$7 = \frac{k}{ - 4} \\ k = 7( - 4) \\ k = - 28$

Thus,

$y = \frac{ - 28}{x}$

When x=5,

$y = \frac{ - 28}{5} \\ y = - 5 \frac{3}{5}$

Answer 2

Answer:

  y = -5.6

Step-by-step explanation:

When x changes by a factor of 5/-4, y changes by a factor that is the inverse of that. (That's what varies inversely means.)

  y = (-4/5)(7) = -28/5

  y = -5.6