In order to factor , first multiply the leading coefficient 1 and the last term -8 to get -8. Now we need to ask ourselves: What two numbers multiply to -8 and add to 9? Lets find out by listing all of the possible factors of -8
Factors:
1,2,4,8,
-1,-2,-4,-8, List the negative factors as well. This will allow us to find all possible combinations
These factors pair up to multiply to -8.
(-1)*(8)=-8
(-2)*(4)=-8
Now which of these pairs add to 9? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 9
| First Number | | | Second Number | | | Sum | | 1 | | | -8 | || | 1+(-8)=-7 | | 2 | | | -4 | || | 2+(-4)=-2 | | -1 | | | 8 | || | (-1)+8=7 | | -2 | | | 4 | || | (-2)+4=2 |
None of these factors add to 9. So the quadratic cannot be factored. |