SOLUTION: Rewrite the middle term as the sum of two terms and then factor completely. 4z squared -18z squared -10z

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Question 115207This question is from textbook Beginning Algebra
: Rewrite the middle term as the sum of two terms and then factor completely.
4z squared -18z squared -10z
This question is from textbook Beginning Algebra

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

Looking at we can see that the first term is and the last term is where the coefficients are 4 and -10 respectively.

Now multiply the first coefficient 4 and the last coefficient -10 to get -40. Now what two numbers multiply to -40 and add to the middle coefficient -18? Let's list all of the factors of -40:



Factors of -40:
1,2,4,5,8,10,20,40

-1,-2,-4,-5,-8,-10,-20,-40 ...List the negative factors as well. This will allow us to find all possible combinations

These factors pair up and multiply to -40
(1)*(-40)
(2)*(-20)
(4)*(-10)
(5)*(-8)
(-1)*(40)
(-2)*(20)
(-4)*(10)
(-5)*(8)

note: remember, the product of a negative and a positive number is a negative number


Now which of these pairs add to -18? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -18

First NumberSecond NumberSum
1-401+(-40)=-39
2-202+(-20)=-18
4-104+(-10)=-6
5-85+(-8)=-3
-140-1+40=39
-220-2+20=18
-410-4+10=6
-58-5+8=3



From this list we can see that 2 and -20 add up to -18 and multiply to -40


Now looking at the expression , replace with (notice adds up to . So it is equivalent to )




Now let's factor by grouping:


Group like terms


Factor out the GCF of out of the first group. Factor out the GCF of out of the second group


Since we have a common term of , we can combine like terms

So factors to


So this also means that factors to (since is equivalent to )

-------------------------------
Answer:

So factors to

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