How do u do #10? plz show on paper

For which rational expression is -2 an excluded value of x?

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document

Rewrite 9 log, x2 in a form that does not use exponents. 9log, x = log, x