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 = -10} $.
$$ a \cdot c = -60 $$Step 3: Find out two numbers that multiply to $ a \cdot c = -60 $ and add to $ b = -11 $.
Step 4: All pairs of numbers with a product of $ -60 $ are:
PRODUCT = -60 | |
-1 60 | 1 -60 |
-2 30 | 2 -30 |
-3 20 | 3 -20 |
-4 15 | 4 -15 |
-5 12 | 5 -12 |
-6 10 | 6 -10 |
Step 5: Find out which factor pair sums up to $\color{blue}{ b = -11 }$
PRODUCT = -60 and SUM = -11 | |
-1 60 | 1 -60 |
-2 30 | 2 -30 |
-3 20 | 3 -20 |
-4 15 | 4 -15 |
-5 12 | 5 -12 |
-6 10 | 6 -10 |
Step 6: Replace middle term $ -11 x $ with $ 4x-15x $:
$$ 6x^{2}-11x-10 = 6x^{2}+4x-15x-10 $$Step 7: Apply factoring by grouping. Factor $ 2x $ out of the first two terms and $ -5 $ out of the last two terms.
$$ 6x^{2}+4x-15x-10 = 2x\left(3x+2\right) -5\left(3x+2\right) = \left(2x-5\right) \left(3x+2\right) $$