JAMB - Mathematics (1987 - No. 23)
Solve the inequality x - 1 > 4(x + 2)
x > -3
x < -3
2 < x < 3
-3 < x < -2
Explication
x - 1 > 4(x + 2) = x - 1 > 4x + 8
4x + 8 < x - 1 = 4x - x < -1 -8
= 3x < -9
∴ x < -3
4x + 8 < x - 1 = 4x - x < -1 -8
= 3x < -9
∴ x < -3