Question

How do you factor completely `4x^2 - 28x +40`?

Answer 1

`4x^2-28x+40=4(x-5)(x-2)`

Explanation:

`4x^2-28x+40=4color(red)((x^2-7x+10))`

`color(red)(x^2-7x+10)=(x-5)(x-2)`

`4x^2-28x+40=4(x-5)(x-2)`

Answer 2

`4x^2-28x+40= color(green)(4(x-5)(x-2))`

Explanation:

Given
`color(white)("XXX")4x^2-28x+40`
Extract the simple constant factor of `4`
`color(white)("XXX")=4(x^2-7x+10)`factor the second part by inspection or use of the quadratic formula to get
`color(white)("XXX")=4(x-2)(x-5)`