SOLUTION: I am having trouble with factoring and solving. Please help. I will greatly appreciate it. Please show work. Factor completely. If the polynomial is prime, state this. Factor

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I am having trouble with factoring and solving. Please help. I will greatly appreciate it. Please show work. Factor completely. If the polynomial is prime, state this. Factor      Log On


   



Question 269103: I am having trouble with factoring and solving. Please help. I will greatly appreciate it. Please show work.
Factor completely. If the polynomial is prime, state this.
Factor completely by grouping.
-36x2+-+30x+%2B+36

Found 2 solutions by Edwin McCravy, AnlytcPhil:
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!

Don't list a bunch of problems.  We will only do one.

Factor completely by grouping. 
-36x2+-+30x+%2B+36

Factor out -6, remembering that when you factor out 
a negative number, all the signs change inside the
parentheses.

-6%286x%5E2%2B5x-6%29

I'll do some coloring:

-6%28red%286%29x%5E2%2B5x-green%286%29%29

Ignoring signs at first, and just using absolute values,
multiply the red 6 by the green 6, getting 36.

Now write down all the ways of two integers
which multiply to give 36:

36*1 = 36
18*2 = 36
12*3 = 36
 9*4 = 36
 6*6 = 36

Now since the sign before the green 6 is -, out
beside those we SUBTRACT the two factors. (If that sign
has been + we would have added them):

36*1 = 36   36-1=35
18*2 = 36   18-2=16
12*3 = 36   12-3= 9 
 9*4 = 36    9-4= 5
 6*6 = 36    6-6= 0

Now we look in the right hand column to see if we can find
the absolute value of the coefficient of the middle term of

-6%286x%5E2%2Bgreen%285x%29-6%29

which is 5, which I have colored green.

Now replace the 5x by 9x-4x 

-6%286x%5E2%2Bgreen%289x-4x%29-6%29

Now I'll do some re-coloring:

-6%28red%286x%5E2%2B9x%29-4x-6%29

Out of the two red terms factor out a 3x

-6%28+red%283x%2A%282x%2B3%29%29-4x-6%29+++

Now out of the remaining black terms, factor out -2,
remembering that when you factor out a negative you change
the signs inside the parentheses:

-6%28red%283x%2A%282x%2B3%29%29-2%282x%2B3%29%29

Now I'll do some more re-coloring

-6%283x%2Agreen%28%282x%2B3%29%29-2%2Agreen%28%282x%2B3%29%29%29

Notice that the green parentheses green%28%282x%2B3%29%29are the same,
and you can factor them out green%28%282x%2B3%29%29 just as you would
factor out just a single letter or number.  When you do you just
put the remaining black factors inside a parentheses:

-6%28green%28%282x%2B3%29%29%283x-2%29%29

or just

-6%282x%2B3%29%283x-2%29

Edwin

Answer by AnlytcPhil(1806) About Me  (Show Source):