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 $\color{blue}{ a = 10 }$ by the constant term $\color{blue}{c = -5} $.
$$ a \cdot c = -50 $$Step 3: Find out two numbers that multiply to $ a \cdot c = -50 $ and add to $ b = 49 $.
Step 4: All pairs of numbers with a product of $ -50 $ are:
PRODUCT = -50 | |
-1 50 | 1 -50 |
-2 25 | 2 -25 |
-5 10 | 5 -10 |
Step 5: Find out which factor pair sums up to $\color{blue}{ b = 49 }$
PRODUCT = -50 and SUM = 49 | |
-1 50 | 1 -50 |
-2 25 | 2 -25 |
-5 10 | 5 -10 |
Step 6: Replace middle term $ 49 x $ with $ 50x-x $:
$$ 10x^{2}+49x-5 = 10x^{2}+50x-x-5 $$Step 7: Apply factoring by grouping. Factor $ 10x $ out of the first two terms and $ -1 $ out of the last two terms.
$$ 10x^{2}+50x-x-5 = 10x\left(x+5\right) -1\left(x+5\right) = \left(10x-1\right) \left(x+5\right) $$