Question

Consider the quadratic expression given below.

Factor the following expression completely.

3x^2-30x-72

Answer 1

`3 x^(2) -30x-72=3( x^(2) -10x-24)`

Using cross multiplication method,

x -12 -12x

x 2 2x


`x^(2)` -24 -10x

Therefore,

`3 x^(2) -30x-72=3( x^(2) -10x-24)`
=3(x-12)(x+2)

Answer 2

The factor form of the given expression is 3(x-12)(x+2).

Explanation:

The given expression is

`3x^2-30x-72`

`3(x^2-10x-24)`

The middle term can be written as -12x+2x.

`3(x^2-12x+2x-24)`

`3[x(x-12)+2(x-12)]`

`3(x-12)(x+2)`

Therefore the factor form of the given expression is 3(x-12)(x+2).