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 $\color{blue}{ a = 6 }$ by the constant term $\color{blue}{c = 8} $.
$$ a \cdot c = 48 $$Step 3: Find out two numbers that multiply to $ a \cdot c = 48 $ and add to $ b = -19 $.
Step 4: All pairs of numbers with a product of $ 48 $ are:
PRODUCT = 48 | |
1 48 | -1 -48 |
2 24 | -2 -24 |
3 16 | -3 -16 |
4 12 | -4 -12 |
6 8 | -6 -8 |
Step 5: Find out which factor pair sums up to $\color{blue}{ b = -19 }$
PRODUCT = 48 and SUM = -19 | |
1 48 | -1 -48 |
2 24 | -2 -24 |
3 16 | -3 -16 |
4 12 | -4 -12 |
6 8 | -6 -8 |
Step 6: Replace middle term $ -19 x $ with $ -3x-16x $:
$$ 6x^{2}-19x+8 = 6x^{2}-3x-16x+8 $$Step 7: Apply factoring by grouping. Factor $ 3x $ out of the first two terms and $ -8 $ out of the last two terms.
$$ 6x^{2}-3x-16x+8 = 3x\left(2x-1\right) -8\left(2x-1\right) = \left(3x-8\right) \left(2x-1\right) $$