Question

Need help: write the expression in a complete factored form: x²-9x+xy-9y

Answer 1

Factor this by grouping. Group the first two terms together and then the second 2 terms together. The idea here is that, after grouping, what you can pull out in both groups is the same. Like this:

`( x^(2) -9x)+(xy-9y)`
Now work on finding a common thing between the 2 groups:

`x(x-9)+y(x-9)`
See, what you have in common there now is the (x-9) that you can factor out:

`(x-9)(x+y)`
And that is factored completely.