SOLUTION: how do you factor 2x^2+11x+5?

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Question 117772This question is from textbook Algebra 1
: how do you factor 2x^2+11x+5? This question is from textbook Algebra 1

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

Looking at 2x%5E2%2B11x%2B5 we can see that the first term is 2x%5E2 and the last term is 5 where the coefficients are 2 and 5 respectively.

Now multiply the first coefficient 2 and the last coefficient 5 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 2x%5E2%2B11x%2B5, replace 11x with 1x%2B10x (notice 1x%2B10x adds up to 11x. So it is equivalent to 11x)

2x%5E2%2Bhighlight%281x%2B10x%29%2B5


Now let's factor 2x%5E2%2B1x%2B10x%2B5 by grouping:


%282x%5E2%2B1x%29%2B%2810x%2B5%29 Group like terms


x%282x%2B1%29%2B5%282x%2B1%29 Factor out the GCF of x out of the first group. Factor out the GCF of 5 out of the second group


%28x%2B5%29%282x%2B1%29 Since we have a common term of 2x%2B1, we can combine like terms

So 2x%5E2%2B1x%2B10x%2B5 factors to %28x%2B5%29%282x%2B1%29


So this also means that 2x%5E2%2B11x%2B5 factors to %28x%2B5%29%282x%2B1%29 (since 2x%5E2%2B11x%2B5 is equivalent to 2x%5E2%2B1x%2B10x%2B5)

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Answer:

So 2x%5E2%2B11x%2B5 factors to %28x%2B5%29%282x%2B1%29