## anonymous one year ago I need to isolate x. How would I do this?

1. anonymous

$\frac{-9x-6}{2\sqrt{x+1}}$

2. amistre64

is this an expression or an equation?

3. anonymous

It's supposed to say =0 after it

4. amistre64

oh, do you know what a fraction is equal to zero?

5. amistre64

**when a fraction is equal to zero

6. anonymous

Are you asking me if I know what happens or do you want to know the variable that would make the denominator 0?

7. amistre64

if we consider a fraction as telling us how many we have, out of how many there are total ... 0 out of anything would equate to having none of it. if we cut a pizza into 6 slices, and we get no slices ... we have 0 out of 6 slices. 0/6

8. amistre64

in order for a fraction to equal zero, it is required that the top must equal zero ...

9. amistre64

or, just mathing it. multiply both sides by the denominator ... the left side cancels out the bottom, and the right side is just a multiplication of 0

10. amistre64

$\frac ab=0$ $b*\frac ab=0*b$ $a=0*b=0$

11. anonymous

So I need to figure out what x value makes the numerator 0?

12. amistre64

correct

13. anonymous

x= -6/9

14. amistre64

then that should be the value of x that makes the left side equate to 0

15. amistre64

as long as it does not zero out the bottom ... or possibly make the sqrt a negative arguement ...

16. anonymous

Awesome. Thank you!

17. amistre64

youre welcome