Step 1 :
After factoring out $ 6 $ we have:
$$ 12z^{2}-6z+42 = 6 ( 2z^{2}-z+7 ) $$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 $\color{blue}{ a = 2 }$ by the constant term $\color{blue}{c = 7} $.
$$ a \cdot c = 14 $$Step 4: Find out two numbers that multiply to $ a \cdot c = 14 $ and add to $ b = -1 $.
Step 5: All pairs of numbers with a product of $ 14 $ are:
PRODUCT = 14 | |
1 14 | -1 -14 |
2 7 | -2 -7 |
Step 6: Find out which factor pair sums up to $\color{blue}{ b = -1 }$
Step 7: Because none of these pairs will give us a sum of $ \color{blue}{ -1 }$, we conclude the polynomial cannot be factored.