using factor theorm factorize the following `y^3−2y^2−29y−42`

Explanation

`y=-2, f(-2)=(-2)^3-2(-2)^2-29(-2)-42`
`=>-8-8+58-42=0`
Therefore (y+2) is a factor of polynomial f(y).
Now,`f(y)=y^2(y+2)+4y(y+2)-21(y+2)`
`(y+2)(y^2-4y-21)`
`(y+2)(y^2-7y+4y-21)`
`(y+2)(y+3)(y-7)`