Question

Resolve the quadratic trinomials into factors:

28 – 31x – 5x²

Answer 1

We have,

28 – 31x – 5x²

– 5x² -31x + 28

5x² + 31x – 28

The coefficient of x² is 5

The coefficient of x is 31

Constant term is -28

So, we express the middle term 31x as -4x + 35x

5x² + 31x – 28 = 5x² – 4x + 35x – 28

= x (5x – 4) + 7 (5x – 4)

= (x + 7) (5x – 4)