Step 1 :
After factoring out $ v^{7} $ we have:
$$ 18v^{9}+33v^{8}+14v^{7} = v^{7} ( 18v^{2}+33v+14 ) $$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 $\color{blue}{ a = 18 }$ by the constant term $\color{blue}{c = 14} $.
$$ a \cdot c = 252 $$Step 4: Find out two numbers that multiply to $ a \cdot c = 252 $ and add to $ b = 33 $.
Step 5: All pairs of numbers with a product of $ 252 $ are:
PRODUCT = 252 | |
1 252 | -1 -252 |
2 126 | -2 -126 |
3 84 | -3 -84 |
4 63 | -4 -63 |
6 42 | -6 -42 |
7 36 | -7 -36 |
9 28 | -9 -28 |
12 21 | -12 -21 |
14 18 | -14 -18 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = 33 }$
PRODUCT = 252 and SUM = 33 | |
1 252 | -1 -252 |
2 126 | -2 -126 |
3 84 | -3 -84 |
4 63 | -4 -63 |
6 42 | -6 -42 |
7 36 | -7 -36 |
9 28 | -9 -28 |
12 21 | -12 -21 |
14 18 | -14 -18 |
Step 7: Replace middle term $ 33 x $ with $ 21x+12x $:
$$ 18x^{2}+33x+14 = 18x^{2}+21x+12x+14 $$Step 8: Apply factoring by grouping. Factor $ 3x $ out of the first two terms and $ 2 $ out of the last two terms.
$$ 18x^{2}+21x+12x+14 = 3x\left(6x+7\right) + 2\left(6x+7\right) = \left(3x+2\right) \left(6x+7\right) $$