Answer: x is doubled.
Explanation:
A proportional relationship between x and y is written as:
y = k*x
where k is called the constant of proportionality.
In this case, we know that we have a proportional relationship between z and x^3
Then:
z = k*x^3
What will happen to x when z is 8 times greater?
Let's rewrite this equation for two new quantities, z' and x'
z' = k*(x')^3
Now we need to replace z' by 8*z, then:
8*z = k*(x')^3
We want to find a relationship between x' and x.
And by the first relationship, we know that:
z = k*x^3
Then we can replace this in the equation "8*z = k*(x')^3" to get:
8*(k*x^3) = k*(x')^3
8*k*x^3 = k*(x')^3
Now we can divide both sides by k, so we get:
8*x^3 = (x')^3
Now we can apply the cubic root to both sides, to get:
∛(8*x^3) = ∛(x')^3
∛(8)*x = x'
2*x = x'
Then when we increase the value of z 8 times, the value of x will be doubled.