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 $\color{blue}{ a = 2 }$ by the constant term $\color{blue}{c = -33} $.
$$ a \cdot c = -66 $$Step 3: Find out two numbers that multiply to $ a \cdot c = -66 $ and add to $ b = -5 $.
Step 4: All pairs of numbers with a product of $ -66 $ are:
PRODUCT = -66 | |
-1 66 | 1 -66 |
-2 33 | 2 -33 |
-3 22 | 3 -22 |
-6 11 | 6 -11 |
Step 5: Find out which factor pair sums up to $\color{blue}{ b = -5 }$
PRODUCT = -66 and SUM = -5 | |
-1 66 | 1 -66 |
-2 33 | 2 -33 |
-3 22 | 3 -22 |
-6 11 | 6 -11 |
Step 6: Replace middle term $ -5 x $ with $ 6x-11x $:
$$ 2x^{2}-5x-33 = 2x^{2}+6x-11x-33 $$Step 7: Apply factoring by grouping. Factor $ 2x $ out of the first two terms and $ -11 $ out of the last two terms.
$$ 2x^{2}+6x-11x-33 = 2x\left(x+3\right) -11\left(x+3\right) = \left(2x-11\right) \left(x+3\right) $$