Answer
x=-5/7
Work Step by Step
5x(x^2-7)= 5(x^3+5) (Using cross product rule)
5x^3-35x=5x^3+25 (Using distributive property , simplify paranthesis)
Subtract 5 x^3 on both sides,
5x^3-35x-5x^3=5x^3+25-5x^3
-35x=25
Dividing both sides by -35, we get
x=-25/35
hence x=-5/7.