Factorize algebraic expressions: 40 + 3x – x2

We have,

40 + 3x – x²

-(x² – 3x – 40)

By considering, p+q = -3 and pq = -40

So we can replace -3x by 5x – 8x

-40 by 5 × -8

-(x² – 3x – 40) = x² + 5x – 8x – 40

= -x (x + 5) – 8 (x + 5)

= -(x – 8) (x + 5)

= (-x + 8) (x + 5)