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