Posted by **John** on Tuesday, October 30, 2007 at 1:18pm.

Ok I got two I need help with :

1. Factor Completely

7x^2 + 49x + 42

I get 7x^2 + 7x + 42x + 42

then 7x(x+1) but the right side is confusing me. I know it should be (x+6).

So the answer is 7x(x+1)(x+6) But I get 7x(x+1) 7(6x+6). What am I doing wrong?

2.Factor completley:

x^10y^3 - 4x^9y^2 - 21x^8y

Totally consfused on this one.

- Algebra -
**bobpursley**, Tuesday, October 30, 2007 at 1:31pm
On the first, factor 42 out of the second paren.

7x(x+1)+ 42(x+1)

(x+1)(7x+42)

now factor 7 out of the second..

7(x+1)(x+6)

Onthe last, factor the common factor x^8*y out

yx^8[(xy)^2 -4xy -21]

The last term factors to (xy-7)(xy+3)

- Algebra -
**Neo**, Tuesday, October 30, 2007 at 1:33pm
Solution for No.1

7x^2 + 49x + 42

7x^2 + 7x + 42x + 42

(7x^2 + 7x) + (42x + 42)

[7x(x+1)+ 42(x+1)]

(7x+42)(x+1)

7(x+6)(x+1)

Solution for No.2

x^10y^3 - 4x^9y^2 - 21x^8y

x^8y (x^2y^2 - 4xy - 21)

x^8y (xy-7)(xy+3)

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