Question

Solve x^2 + 4x – 5 < 0.

–5 < x < 1

x < –5 or x > 1

x < 1

x > –5

Answer 1

Factor: x^2 + 4x − 5 = (x + 5)(x − 1).
For (x + 5)(x − 1) < 0 the factors must have opposite signs, which occurs for −5 < x < 1.

Answer: −5 < x < 1.