algebra direct inverse?
y varies directly as the cube of x. if x is doubled what is the effect on y?
y = KX to the 3rd is obvious. so i'm stuck and can't proceed. help on the steps??
Update:still don't know where the 8y comes from
y varies directly as the cube of x. if x is doubled what is the effect on y?
y = KX to the 3rd is obvious. so i'm stuck and can't proceed. help on the steps??
Update:still don't know where the 8y comes from
Comments
y = kx^3
x is doubled so replace x with 2x then compare the result.
k(2x)^3
= k(8x^3)
= 8kx^3
= 8y
We see that y increases by factor of 8.
if x is doubled, then the new X is 2x.
Cubing this will give 8x^3.
thus, y will be 8 times the original y.
y = kx^3
Double x:
y = k(2x)^3
y = k(2^3)(x^3)
y = 8kx^3
Therefore, if x is doubled, y is increased by a factor of 8.