## owlet one year ago help, I'm stuck with the question below. About Inverse Function. I just need help getting the inverse of the function.

1. owlet

2. anonymous

this has to be done algebraically?

3. owlet

yeah, idk how to do it

4. owlet

i'm not sure how to do the sqrt part along with the y^3 part

5. anonymous

not really sure how to go about solving the equation for y, but they're basically asking you to find where y = 11. I graphed it and backed out a solution that way. not exactly efficient

6. owlet

i tried doing that also. First I planned to solve the value of x when f(x)=11 , so that I could just switch it. But I'm stuck. We're not allowed to use any devices during exams/tests/quizzes, so I wanted to learn how to do this.

7. anonymous

I was thing a change of variable, but the equations I ended up with weren't much better than this one

8. anonymous

i have a suggestion

9. anonymous

set $x^3+\sqrt{x+7}=11$ and solve for $$x$$

10. anonymous

you can do it using algebra, but i would not there is a simpler way

11. owlet

as i've said before, that's the first thing I tried. sqrt(x+7)=11-x^3 then if I square both sides,I will still get a not so good set up which confused me.

12. anonymous

since 11 is an integer, $$x+7$$ must be a perfect square

13. anonymous

think of a number (gotta be pretty small) that when added to 7 gives a perfect square you will probably get it on the first try

14. owlet

7+2=9, so 2?

15. anonymous

an easy check now right?

16. anonymous

$2^3+\sqrt{2+7}=?$

17. owlet

8+3=11.. so its really 2 wait that's it??

18. anonymous

lol yeah, that's it

19. owlet

oh okay thanks.. it's like a trial and error method then