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