Question

Suppose y varies directly as x, and y =16 when x=8. Find y when x=16

Answer 1

 y varies directly as x, and y =16 when x=8. Find y when x=16
y is double x
so when x=16
y=16x2 which equals 32

Answer 2

For this case, since the variation is direct then we have a relation of the form:

$y = kx$

Where,

k: proportionality constant

To find k we substitute the following data:

y = 16 when x = 8

We have then:

$16 = k8$

Clearing the value of k we have:

$k = \frac{16}{8}\\k = 2$

Then, the equation is:

$y = 2x$

Substituting the value of x = 16 we have:

$y = 2 (16)\\y = 32$

Answer:

The value of y for x = 16 is:

$y = 32$