SOLUTION: Given that y directly with the square of x, and y=10 when x=5, find:
a) y when x=20
b)x when y=40
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Question 1174352: Given that y directly with the square of x, and y=10 when x=5, find:
a) y when x=20
b)x when y=40
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
y=kx^2
10=k*5^2
k=10/25 or 0.4
so y=0.4*20^2=160; when x goes from 5 to 20, it increases 4 fold; y will increase 16 fold, from 10 to 160
40=0.4*x^2
100=x^2
x=10
When y increases 4 fold, x increases 2 fold.
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