SOLUTION: Factor each expression. 5x2+16x+3

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Question 139593This question is from textbook
: Factor each expression.
5x2+16x+3
This question is from textbook

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

Looking at 5x%5E2%2B16x%2B3 we can see that the first term is 5x%5E2 and the last term is 3 where the coefficients are 5 and 3 respectively.

Now multiply the first coefficient 5 and the last coefficient 3 to get 15. Now what two numbers multiply to 15 and add to the middle coefficient 16? Let's list all of the factors of 15:



Factors of 15:
1,3,5,15

-1,-3,-5,-15 ...List the negative factors as well. This will allow us to find all possible combinations

These factors pair up and multiply to 15
1*15
3*5
(-1)*(-15)
(-3)*(-5)

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


Now which of these pairs add to 16? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 16

First NumberSecond NumberSum
1151+15=16
353+5=8
-1-15-1+(-15)=-16
-3-5-3+(-5)=-8



From this list we can see that 1 and 15 add up to 16 and multiply to 15


Now looking at the expression 5x%5E2%2B16x%2B3, replace 16x with 1x%2B15x (notice 1x%2B15x adds up to 16x. So it is equivalent to 16x)

5x%5E2%2Bhighlight%281x%2B15x%29%2B3


Now let's factor 5x%5E2%2B1x%2B15x%2B3 by grouping:


%285x%5E2%2B1x%29%2B%2815x%2B3%29 Group like terms


x%285x%2B1%29%2B3%285x%2B1%29 Factor out the GCF of x out of the first group. Factor out the GCF of 3 out of the second group


%28x%2B3%29%285x%2B1%29 Since we have a common term of 5x%2B1, we can combine like terms

So 5x%5E2%2B1x%2B15x%2B3 factors to %28x%2B3%29%285x%2B1%29


So this also means that 5x%5E2%2B16x%2B3 factors to %28x%2B3%29%285x%2B1%29 (since 5x%5E2%2B16x%2B3 is equivalent to 5x%5E2%2B1x%2B15x%2B3)


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Answer:

So 5x%5E2%2B16x%2B3 factors to %28x%2B3%29%285x%2B1%29