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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