factoring polinomials by grouping HELP!!!

bnorth22

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Oct 22, 2006
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According to my text book the step by step solution for 4x-4y+ax-ay is as follows:

Step 1: Group terms with the common factors. In this problem the first two terms have a common factor of 4 and the last two terms have a common factor of a.

. . .4x - 4y + ax - ay = (4x - 4y) + (ax - ay)

Step 2: In each grouping, factor out the common factor.


. . .(4x - 4y) + (ax - ay) = 4(x - y) + a(x - y)

Step 3: Factor out the common factor that remains.


. . .4(x - y) + a(x - y) = (x - y)(4 + a)
This is the step I don't understand. I'm not sure what was factored from
4(x - y) + a(x - y) to make (x - y)(4 + a). The book dosen't eloborate any farther than step three.

Please someone help me.
 
In 4z + az, what is the common factor? What is left once you take that common factor out front?

In 4(x - y) + a(x - y), what is the common factor? What is left once you take that common factor out front?

Eliz.
 
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