Question

Prove that 3(x+1)(x+7)-(2x+5)² is never positive

Answer 1

Step-by-step explanation:

3(x + 1)(x + 7) − (2x + 5)²

3(x² + 8x + 7) − (4x² + 20x + 25)

3x² + 24x + 21 − 4x² − 20x − 25

-x² + 4x − 4

-(x² − 4x + 4)

-(x − 2)²

A squared number is never negative (provided x is a real number), so -(x − 2)² is never positive.

Answer 2

Answer:

-27x - 219

Step-by-step explanation:

3x+3 * 3x+21 - 6x+15

9x+6 - (6x+15 * 6x+15)

9x+6 - 36x+325

-27x - 219