# SOLUTION: factor completely: x^2+9x=8

Algebra ->  Algebra  -> Polynomials-and-rational-expressions -> SOLUTION: factor completely: x^2+9x=8      Log On

 Ad: Algebrator™ solves your algebra problems and provides step-by-step explanations! Ad: Algebra Solved!™: algebra software solves algebra homework problems with step-by-step help!

 Algebra: Polynomials, rational expressions and equations Solvers Lessons Answers archive Quiz In Depth

Question 101318: factor completely:
x^2+9x=8

You can put this solution on YOUR website!

Subtract 8 from both sides

Now let's factor

Solved by pluggable solver: Factoring using the AC method (Factor by Grouping)
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.