If y is directly proportional to x square and y equal 1/8 when x = 1/2 what is the positive value of x when y it was 9/2? a) 3/4
b) 3/2
c) 9/4
d) 3

d

Step-by-step explanation:

Given y is directly proportional to x² then the equation relating them is

y = kx² ← k is the constant of proportion

To find k use the condition y = when x = , then

= k( )² = k ( multiply both sides by 8 )

1 = 2k ( divide both sides by 2 )

k =

y = x² ← equation of proportion

When y = , then

= x² ( multiply both sides by 2 )

9 = x² ( take the square root of both sides )

x = ± = ± 3

with positive value x = 3 → d

y=3x+4

step-by-step explanation:

given the points a(0,4) and b(-4, -8)

eqn of line ab: (y-4)/(x-0)=(-8-4)/(-4-0)

(y-4)/x=-12/-4=3

y=3x+4