1. Dec 5, 2012

### Coco12

Is the answer to sqrt -81y^3 : y sqrt-81y? or is there no real solutions?

sqrt 2n-5 - sqrt 3n+4=2
I worked it out and cant seem to get an answer. Is there no real solutions?

2. Dec 5, 2012

### Staff: Mentor

if y<0, then $\sqrt{-81y^3}=|y|\sqrt{-81y}$, otherwise the square root is not defined in the real numbers.

Your equation has no real solutions. You can check this with WolframAlpha, for example.

3. Dec 5, 2012

### Coco12

thank you so much, that WolframAlpha thing is very useful!

4. Dec 5, 2012

### dextercioby

That $\sqrt{-81 y}$ can be further simplified by noting that 92 = 81 and -y = |y| , for y smaller or equal to 0.