Answer:
x = - 7, x = 0 and x = 4
Step-by-step explanation:
Factor the polynomial and solve for x
Given
x³ + 3x² - 28x = 0 ← factor out x from each term
x(x² + 3x - 28) = 0 ← factor the quadratic
x(x + 7)(x - 4) = 0
Equate each factor to zero and solve for x
x = 0
x + 7 = 0 ⇒ x = - 7
x - 4 = 0 ⇒ x = 4
These are the 3 points where the graph crosses the x- axis
