Answer:
u = √x
u² - 15u +50
Solutions at x = 25 and x = 100
Explanation:
Make the substitution u = √x
Then the quadratic equation in u is
u² - 15u +50
because u² = (√x)² =x
and 15√x = 15u
This can be solved by factorization
u² - 15u +50 = (u -5)(u-10) = 0
So two solutions are u = 5and u = 10
Since u = √x , x = u² and therefore the two solutions for x are
5² = 25 and
10² = 100