SOLUTION: Factor completely. n squared - 11n + 10

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Question 114999: Factor completely.
n squared - 11n + 10

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

Looking at n%5E2-11n%2B10 we can see that the first term is n%5E2 and the last term is 10 where the coefficients are 1 and 10 respectively.

Now multiply the first coefficient 1 and the last coefficient 10 to get 10. Now what two numbers multiply to 10 and add to the middle coefficient -11? Let's list all of the factors of 10:



Factors of 10:
1,2,5,10

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

These factors pair up and multiply to 10
1*10
2*5
(-1)*(-10)
(-2)*(-5)

note: remember two negative numbers multiplied together make a positive number


Now which of these pairs add to -11? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -11

First NumberSecond NumberSum
1101+10=11
252+5=7
-1-10-1+(-10)=-11
-2-5-2+(-5)=-7



From this list we can see that -1 and -10 add up to -11 and multiply to 10


Now looking at the expression n%5E2-11n%2B10, replace -11n with -1n%2B-10n (notice -1n%2B-10n adds up to -11n. So it is equivalent to -11n)

n%5E2%2Bhighlight%28-1n%2B-10n%29%2B10


Now let's factor n%5E2-1n-10n%2B10 by grouping:


%28n%5E2-1n%29%2B%28-10n%2B10%29 Group like terms


n%28n-1%29-10%28n-1%29 Factor out the GCF of n out of the first group. Factor out the GCF of -10 out of the second group


%28n-10%29%28n-1%29 Since we have a common term of n-1, we can combine like terms

So n%5E2-1n-10n%2B10 factors to %28n-10%29%28n-1%29


So this also means that n%5E2-11n%2B10 factors to %28n-10%29%28n-1%29 (since n%5E2-11n%2B10 is equivalent to n%5E2-1n-10n%2B10)