Question

How do you multiply and simplify `\frac { 7x + 21} { 1- x } \cdot \frac { x - 1} { x + 3}`?

Answer 1

Expression `= -7` `{x!=-3 or 1}`

Explanation:

Expression `= (7x+21)/(1-x) * (x-1)/(x+3)`

`= (7(x+3))/(1-x) * (-(1-x))/(x+3)`

`= (-7(cancel(x+3)))/cancel((1-x)) * cancel((1-x))/cancel(x+3)` `{x!=-3 or 1}`

`=-7`