Step 1 :
After factoring out $ 4 $ we have:
$$ 16x^{2}+32x+12 = 4 ( 4x^{2}+8x+3 ) $$Step 2 :
Step 2: Identify constants $ a $ , $ b $ and $ c $.
$ a $ is a number in front of the $ x^2 $ term $ b $ is a number in front of the $ x $ term and $ c $ is a constant. In this case:
Step 3: Multiply the leading coefficient $\color{blue}{ a = 4 }$ by the constant term $\color{blue}{c = 3} $.
$$ a \cdot c = 12 $$Step 4: Find out two numbers that multiply to $ a \cdot c = 12 $ and add to $ b = 8 $.
Step 5: All pairs of numbers with a product of $ 12 $ are:
PRODUCT = 12 | |
1 12 | -1 -12 |
2 6 | -2 -6 |
3 4 | -3 -4 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = 8 }$
PRODUCT = 12 and SUM = 8 | |
1 12 | -1 -12 |
2 6 | -2 -6 |
3 4 | -3 -4 |
Step 7: Replace middle term $ 8 x $ with $ 6x+2x $:
$$ 4x^{2}+8x+3 = 4x^{2}+6x+2x+3 $$Step 8: Apply factoring by grouping. Factor $ 2x $ out of the first two terms and $ 1 $ out of the last two terms.
$$ 4x^{2}+6x+2x+3 = 2x\left(2x+3\right) + 1\left(2x+3\right) = \left(2x+1\right) \left(2x+3\right) $$