Answer:
x = 9 or x = 0 or x = -2
Explanation:
Solve for x:
3 x^3 - 21 x^2 - 54 x = 0
The left hand side factors into a product with four terms:
3 x (x - 9) (x + 2) = 0
Divide both sides by 3:
x (x - 9) (x + 2) = 0
Split into three equations:
x - 9 = 0 or x = 0 or x + 2 = 0
Add 9 to both sides:
x = 9 or x = 0 or x + 2 = 0
Subtract 2 from both sides:
Answer: x = 9 or x = 0 or x = -2