Question

solve for (x).

(x^2 + 4x - 21 = 0)

-3, -7
-3, 7
3, -7
3, 7

Explanation:

Factor the quadratic equation

$$ x^2 + 4x - 21 = 0 $$

$$ (x + 7)(x - 3) = 0 $$

Solve for x

$$ x + 7 = 0 \implies x = -7 $$

$$ x - 3 = 0 \implies x = 3 $$

$$ x = 3, -7 $$

Answer:

• -3, -7
• -3, 7
• 3, -7 (Correct answer)
• 3, 7