117k views
3 votes
What is x= if (8x^3-9)^3=5832

User Robbie Dee
by
8.0k points

1 Answer

4 votes

(8x^3-9)^3=5832

Cube root each side.
∛5832 = 18. You can prime factorize to find this.


8x^3-9=18

Add 9 to each side.


8x^3=27

Divide by 8.


x^3=\frac{27}8

Cube root each side.


\boxed{x=\frac{3}2}

Note that radicals with an odd index (cube roots, 5th, 7th, etc.) don't leave a plus-minus...If there's an even number all of the negatives cancel, but if it's odd, it won't, just as with exponents.

User BALAJI PILLAI
by
8.4k points