Mathematics

y is directly proportional to x².
It is know that y=5 for a particular value of x.
Find the value of y when x is halved.

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  1. y = kx^2
    if you replace x with x/2, then the new y is
    k(x/2)^2 = 1/4 kx^2
    so the y value is divided by 4

    think of the way area scales when the linear dimensions are changed.

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