if y varies directly to the square of x and y=16 when x=40 then find x when y=64

Question

if y varies directly to the square of x and y=16 when x=40 then find x when y=64

Answer 1

Y = KX²

 

(16) = K (1600)

 

K = 16/1600

 

Therefore:

 

Y = KX²

 

64 = (16/1600) X

 

64 / (16/1600) = X

 

 

X = 64 x (1600/16) = 6400

 

ANS: 6400