Question

Factoring grouping 3x^3+5x^2+12x+20

Answer 1

Consider polynomial
`3x^3+5x^2+12x+20.` Group first two terms and last two terms:

`3x^3+5x^2+12x+20=(3x^3+5x^2)+(12x+20).`

Terms in first brackets have the common factor
`x^2` and terms in second brackets have common factor
`4.` Then

`(3x^3+5x^2)+(12x+20)=x^2(3x+5)+4(3x+5).`

Now you can see the common brackets
`3x+5,` that gives you

`x^2(3x+5)+4(3x+5)=(3x+5)(x^2+4).`

Answer:
`3x^3+5x^2+12x+20=(3x+5)(x^2+4).`