Step 1: 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 2: Multiply the leading coefficient $\color{blue}{ a = 35 }$ by the constant term $\color{blue}{c = 6} $.
$$ a \cdot c = 210 $$Step 3: Find out two numbers that multiply to $ a \cdot c = 210 $ and add to $ b = 47 $.
Step 4: All pairs of numbers with a product of $ 210 $ are:
PRODUCT = 210 | |
1 210 | -1 -210 |
2 105 | -2 -105 |
3 70 | -3 -70 |
5 42 | -5 -42 |
6 35 | -6 -35 |
7 30 | -7 -30 |
10 21 | -10 -21 |
14 15 | -14 -15 |
Step 5: Find out which factor pair sums up to $\color{blue}{ b = 47 }$
PRODUCT = 210 and SUM = 47 | |
1 210 | -1 -210 |
2 105 | -2 -105 |
3 70 | -3 -70 |
5 42 | -5 -42 |
6 35 | -6 -35 |
7 30 | -7 -30 |
10 21 | -10 -21 |
14 15 | -14 -15 |
Step 6: Replace middle term $ 47 x $ with $ 42x+5x $:
$$ 35x^{2}+47x+6 = 35x^{2}+42x+5x+6 $$Step 7: Apply factoring by grouping. Factor $ 7x $ out of the first two terms and $ 1 $ out of the last two terms.
$$ 35x^{2}+42x+5x+6 = 7x\left(5x+6\right) + 1\left(5x+6\right) = \left(7x+1\right) \left(5x+6\right) $$