Understanding factoring!!?

Question

could someone please explain factoring to me? i have had so many people try and i still dont understand it.

i guess there are four methods you can use.

gcf

difference of 2 squares

testing factors

trinomial square

4x^2 + 5x - 9

y^2 - 9z^2

9x^2 - 16y^2

4y^2 + 36y + 81

y^2 + y - 20

please dont just do the problems. i really really want to understand this. thank you!

Answer 1

1.  (x - 1) (4x + 9)

2.  (y + 3z) (y - 3z)

3.  (3x - 4y) (3x + 4y)

4.  (2y + 9) (2y + 9)

5.  (y + 5) (y - 4)

when you have equations that need to be factored, you need to look at the squared number and the last number. These two will give you a starting point.  For the first equation, 4 is a square (2^2), so naturally you wan to start with (2x + __) (2x - __), but when that doesn't work after you check your work, you need to think of other numbers that will give you 4, in this case 1 and 4.  The last number is a product of two numbers.  This is where you select the numbers that will go in your factors.  

Answer 2

just ask your teacher for help!!!! It's not that scary ;)