Step 1 :
After factoring out $ b $ we have:
$$ 3b^{3}-13b^{2}+10b = b ( 3b^{2}-13b+10 ) $$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 $\color{blue}{ a = 3 }$ by the constant term $\color{blue}{c = 10} $.
$$ a \cdot c = 30 $$Step 4: Find out two numbers that multiply to $ a \cdot c = 30 $ and add to $ b = -13 $.
Step 5: All pairs of numbers with a product of $ 30 $ are:
| PRODUCT = 30 | |
| 1 30 | -1 -30 |
| 2 15 | -2 -15 |
| 3 10 | -3 -10 |
| 5 6 | -5 -6 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = -13 }$
| PRODUCT = 30 and SUM = -13 | |
| 1 30 | -1 -30 |
| 2 15 | -2 -15 |
| 3 10 | -3 -10 |
| 5 6 | -5 -6 |
Step 7: Replace middle term $ -13 x $ with $ -3x-10x $:
$$ 3x^{2}-13x+10 = 3x^{2}-3x-10x+10 $$Step 8: Apply factoring by grouping. Factor $ 3x $ out of the first two terms and $ -10 $ out of the last two terms.
$$ 3x^{2}-3x-10x+10 = 3x\left(x-1\right) -10\left(x-1\right) = \left(3x-10\right) \left(x-1\right) $$