Help me solve this im totally confused..

[Amir]

[MATH]\sqrt[3]{x-9}-\sqrt[3]{x+9}-\sqrt[3]{9}=0[/MATH]

 

[Steven G]

Try bringing one term to the right side and cubing both sides.

What have you tried to solve your problem. Please post your work. Thanks.

 

[HallsofIvy]

[MATH]\sqrt[3]{x-9}-\sqrt[3]{x+9}-\sqrt[3]{9}=0[/MATH]

Bringing one term to the right side, as Jomo suggested,
[math]\sqrt[3]{x- 9}- \sqrt[3]{9}= \sqrt[3]{x+ 9}[/math]
Now cube both sides. Be careful, that is not trivial!
[math](a- b)^3= a^3- 3a^2b+ 3ab^2- b^3[/math][math](^3\sqrt[3]{x- 9}- \sqrt[3]{9})^3= (x- 9)- 2(\sqrt[3]{x- 9})^2\sqrt[3]{9}+ 3\sqrt[3]{x- 9}(\sqrt[3]{9})^2- 9[/math].

There is still a lot of work to be done!

 

[apple2357]

You might want to explore it graphically using a graph plotter first? Just to give you a feel for what might be going on.

 

[apple2357]