# Algebra

posted by John

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.

1. bobpursley

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)

2. Neo

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)

## Similar Questions

1. ### Algebra

The area of a square garden in square feet is 49x^2-14x+1. Find the dimensions of the garden in terms of x. FActor the quadratic:(7x-1)^2 Gee, a square. the dimensions are 7x-1 on each side. FActor the quadratic:(7x-1)^2 the dimensions …
2. ### algebra

Two questions actually. Please only respond with step-by-step answers. Feel free to change the numbers, I just need to know how to do it... 1.) Factor Completely: 4a^2 + 81 - 36a 2.) In a right triangle, find the length of the side …
3. ### Algebra

Andrew factored the expression 28x^3-42x^2+35x as 7x(4x^2+6x-5). But when Melissa applied the distributive law and multiplied out 7x(4x^2+6x-5) , she got 28x^3+42x^2-35x ; thus, Andrewâ€™s solution does not appear to check. Why is …
4. ### Pre Calculus

factor completely 1. x^3-9x^2 2. 36x^6-49x^4
5. ### math

I need help with these two problems please. Completely factor the polynomial. 8x^3+16^2+8x+16 Factor the trinomial completely. y^3-14y^2+48y
6. ### Algebra

I have two problems that I need some help with. I believe I got to the answer but not quite sure if its right. I need to expand and evaluate each series. 1. There is an E like symbol that has a 7 at the top. On the bottom k=1 and on …
7. ### algebra

I need to factor (my last post was incorrect) 24x^2 + 42x + 15
8. ### algebra

factor completely. -49x^2-35x-6 Please help with this, I know you multiply the two outer numbers which =-294, I am just having trouble finding a pair of factors of 294 that sum add up to 35. thanks
9. ### Algebra 1

Factor 24x^2-42x I know how to factor but there is only two terms?
10. ### ALGEBRA

Factor completely 9x^2 + 42x + 49. A. (3x + 7)(3x − 7) B. (9x − 7)(9x − 7) C. (3x + 7)(3x + 7) D. (9x + 7)(9x + 7) HELP PLEASE DON'T UNDERSTAND

More Similar Questions