Algebra 1
posted by Tamir on .
Hello. Can someone check my answers to the following
Factor each of the following
1. a^2  9
My answer
a^2  9 = 0
(a  3)a + 3)
2. 4a^2  4a+1
My Answer
4a^2  4a + 1
= 4a^2  2a  2a + 1
= 2a(2a  1)  1(2a  1)
= (2a  1)(2a  1)
3. 72  22x + x^2
My answer
72  22x + x^2
= x^2  22x + 72
= x^2  18x  4x + 72
= x (x  18)  4 (x  18)
= (x  4) (x  18)
4. Solve by factoring 3x^2 + 5x  2 =0
My Answer
3x^2+5x2=0
=3x^2+6xx2
=3x(x2)(x+2)
=(3x1)(x+2)
Oh, the x^2 is squared.
Thanks in advance.

1. correct
2. correct
3. correct but could go from 2nd line to last
4. correct
You know you can check these by foiling, right? (when you multiply out your answers and then see if you got what you started with)