It seems that $ 10b^{2}-9b-2 $ cannot be factored out.
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 = -2} $.
$$ a \cdot c = -20 $$Step 3: Find out two numbers that multiply to $ a \cdot c = -20 $ and add to $ b = -9 $.
Step 4: All pairs of numbers with a product of $ -20 $ are:
PRODUCT = -20 | |
-1 20 | 1 -20 |
-2 10 | 2 -10 |
-4 5 | 4 -5 |
Step 5: Find out which factor pair sums up to $\color{blue}{ b = -9 }$
Step 6: Because none of these pairs will give us a sum of $ \color{blue}{ -9 }$, we conclude the polynomial cannot be factored.