If y varies directly as x squared and y equals 150 when x equals 5 find y when x equals 4?

Answer 1

First you need to know that the equation you are looking for is y = kx^2.

Then you need to substitute the numbers in:

y = kx^2

150 = k5^2

150 = k25

6 = k

Now that you know k, resubstitute it for the new value of y when x = 4:

y = kx^2

y = (6)(4)^2

y = (6)(16)

y = 96