Question

Factorise the following: i) 42- x -x^2 ii) 16x^2 + 25- 40x

Answer 1

-(x+6)(x+7)

(4x-5)(4x-5)

Explanation:

Answer 2

`(-x+6)(x+7)`

`(4x-5)(4x-5)`

Explanation:

`-x^2-x+42`

`-\left(x^2+x-42\right)`

`-\left(x-6\right)\left(x+7\right)`

`(-x+6)(x+7)`

`16x^2 + 25- 40x`

`16x^2-40x+25`

`\left(4x\right)^2-2\cdot \:4x\cdot \:5+5^2`

`\left(4x-5\right)^2`

`(4x-5)(4x-5)`