<PRE><B>Question 70783</B>
Factor by grouping:

3b^2+16b+5
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Think of two numbers whose product is 3*5=15
and whose sum is 16
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The numbers are 1 and 15
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Replace 16b in the problem with b+15b to get:
3b^2+b+15b+5
Factor the 1st two terms and the last two terms separately:
b(3b+1) + 5(3b+1)
Factor out the common factor of (3b+1) to get:
(3b+1)(b+5
Those are the factors you want.
This method is called the AC method because you wanted to find
two numbers whose product was AC=3*5=15.
Cheers,
Stan H.</PRE>