Giải các bất phương trình sau: a) (3x + 1)(x + 2) > x(3x – 2) + 1;

a) (3x + 1)(x + 2) > x(3x – 2) + 1;

3x² + 7x + 2 > 3x² – 2x + 1

7x + 2 > –2x + 1

7x + 2x > 1 – 2

9x > –1

x>−19

Vậy x>−19.

b) 2x(x + 1) + 3 < x(2x + 5) – 7.

2x² + 2x + 3 < 2x² + 5x – 7

2x + 3 < 5x – 7

2x – 5x < –7 – 3

–3x < –10

x>−10−3

x>103

Vậy x>103.