Question

Z varies directly as x squared. if z=36 when x=2, find z when x=3.

Answer 1

z ∝ x^2

Z = kx^2

when z = 36 and x = 2, substitute into the equation above

i.e, 36 = k x 2^2

36 = 4k

therefore k = 9

so the equation becomes

Z = 9x^2

when x =3

Z = 9 x 3^2

Z = 9 x 9

Z = 81

Explanation: