# college algebra

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if y vaires directly as x^2 and y=20 when x=4, find y when x=7?

I got 61.25 but was not sure if it was correct...

• college algebra -

y = kx^2
20 = k*16
k = 5/4

so, y = 5/4 x^2
y(7) = 5/4 * 49 = 61.25

Good job.

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