Step 1 :
After factoring out $ -1 $ we have:
$$ -7x^{2}+17x-10 = - ~ ( 7x^{2}-17x+10 ) $$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 $\color{blue}{ a = 7 }$ by the constant term $\color{blue}{c = 10} $.
$$ a \cdot c = 70 $$Step 4: Find out two numbers that multiply to $ a \cdot c = 70 $ and add to $ b = -17 $.
Step 5: All pairs of numbers with a product of $ 70 $ are:
PRODUCT = 70 | |
1 70 | -1 -70 |
2 35 | -2 -35 |
5 14 | -5 -14 |
7 10 | -7 -10 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = -17 }$
PRODUCT = 70 and SUM = -17 | |
1 70 | -1 -70 |
2 35 | -2 -35 |
5 14 | -5 -14 |
7 10 | -7 -10 |
Step 7: Replace middle term $ -17 x $ with $ -7x-10x $:
$$ 7x^{2}-17x+10 = 7x^{2}-7x-10x+10 $$Step 8: Apply factoring by grouping. Factor $ 7x $ out of the first two terms and $ -10 $ out of the last two terms.
$$ 7x^{2}-7x-10x+10 = 7x\left(x-1\right) -10\left(x-1\right) = \left(7x-10\right) \left(x-1\right) $$