Step 1 :
After factoring out $ -2x $ we have:
$$ -4x^{3}-10x^{2}-6x = -2x ( 2x^{2}+5x+3 ) $$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 $\color{blue}{ a = 2 }$ by the constant term $\color{blue}{c = 3} $.
$$ a \cdot c = 6 $$Step 4: Find out two numbers that multiply to $ a \cdot c = 6 $ and add to $ b = 5 $.
Step 5: All pairs of numbers with a product of $ 6 $ are:
PRODUCT = 6 | |
1 6 | -1 -6 |
2 3 | -2 -3 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = 5 }$
PRODUCT = 6 and SUM = 5 | |
1 6 | -1 -6 |
2 3 | -2 -3 |
Step 7: Replace middle term $ 5 x $ with $ 3x+2x $:
$$ 2x^{2}+5x+3 = 2x^{2}+3x+2x+3 $$Step 8: Apply factoring by grouping. Factor $ x $ out of the first two terms and $ 1 $ out of the last two terms.
$$ 2x^{2}+3x+2x+3 = x\left(2x+3\right) + 1\left(2x+3\right) = \left(x+1\right) \left(2x+3\right) $$