Question

Solve the quadratic by factoring.
5, x, squared, plus, 9, x, minus, 4, equals, 3, x, plus, 4
5x
2
+9x−4=3x+4

Answer 1

Start with
5x^2 + 9x − 4 = 3x + 4.

Bring all terms to one side:
5x^2 + 9x − 4 − 3x − 4 = 0
→ 5x^2 + 6x − 8 = 0.

Factor by grouping (or find numbers whose product is −40 and sum is 6: 10 and −4):
5x^2 + 10x − 4x − 8 = 0
→ 5x(x + 2) − 4(x + 2) = 0
→ (5x − 4)(x + 2) = 0.

So x = 4/5 or x = −2.