Step 1 :
After factoring out $ x $ we have:
$$ 2x^{3}-5x^{2}-52x = x ( 2x^{2}-5x-52 ) $$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 $\color{blue}{ a = 2 }$ by the constant term $\color{blue}{c = -52} $.
$$ a \cdot c = -104 $$Step 4: Find out two numbers that multiply to $ a \cdot c = -104 $ and add to $ b = -5 $.
Step 5: All pairs of numbers with a product of $ -104 $ are:
PRODUCT = -104 | |
-1 104 | 1 -104 |
-2 52 | 2 -52 |
-4 26 | 4 -26 |
-8 13 | 8 -13 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = -5 }$
PRODUCT = -104 and SUM = -5 | |
-1 104 | 1 -104 |
-2 52 | 2 -52 |
-4 26 | 4 -26 |
-8 13 | 8 -13 |
Step 7: Replace middle term $ -5 x $ with $ 8x-13x $:
$$ 2x^{2}-5x-52 = 2x^{2}+8x-13x-52 $$Step 8: Apply factoring by grouping. Factor $ 2x $ out of the first two terms and $ -13 $ out of the last two terms.
$$ 2x^{2}+8x-13x-52 = 2x\left(x+4\right) -13\left(x+4\right) = \left(2x-13\right) \left(x+4\right) $$