If a varies directly with x squared, and a = 8 when x = 4 find the constant variation of k

k = 0.5

Step-by-step explanation:

Given a varies directly with x² then the equation relating them is

a = kx² ( k is the constant of variation )

To find k use the condition a = 8 when x = 4 , then

8 = k × 4² = 16k ( divide both sides by 16 )

0.5 = k

ruth is 6 years old

step-by-step explanation:

6 + 24 = 30,   so 6/30 = .2  

if you do 1/5 it also equals .2, so that is the answer.

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15