Factoring a Polynomial.

[colormekaylee]

y^2(y+1) - 4y(y+1) - 21(y+1)

So far, I have (y+1) (y^2 - 4y - 21)

(y+1)(y-7)(y+3) I'm not sure if im on the right track, or if I allready messed up. Help please!

 

[wjm11]

y^2(y+1) - 4y(y+1) - 21(y+1)

So far, I have (y+1) (y^2 - 4y - 21)

(y+1)(y-7)(y+3)

Your work is correct. Good job!

 

[Deleted member 4993]

y^2(y+1) - 4y(y+1) - 21(y+1)

So far, I have (y+1) (y^2 - 4y - 21)

(y+1)(y-7)(y+3) I'm not sure if im on the right track,

The way to find it yourself is to multiply the whole thing back out and check:

(y+1)(y-7)(y+3)

=(y+1)[y * y + 3 * y - 7 * y + (-7)(3)]

= (y+1)[y[sup:3eka6nhl]2[/sup:3eka6nhl] - 4y - 21]

= (y+1) * y[sup:3eka6nhl]2[/sup:3eka6nhl] - (y+1) * 4y - (y+1) * 21

and this is what you started with - so you are most probably correct...
or if I allready messed up. Help please!