# Math Help - cubed root

1. ## cubed root

$\sqrt{6x+9}+5 = 2$

2. it i ssuposed to be a cubed root not a sqaure root i did not know how to make the formula with a square root

3. Originally Posted by imbadatmath
it i ssuposed to be a cubed root not a sqaure root i did not know how to make the formula with a square root
this is very similar to the question we did for your earlier with the square root. subtract 5 from both sides, and then cube both sides

use $$\sqrt[3]{6x + 9}$$ to get $\sqrt[3]{6x + 9}$

4. oo ok thx

5. i subtracted 3 from both sides then i multiplied both sides by 3 so i got the equation to be

6x+9=-27
i then subtracted 9 from both sides
6x=-36
i then divided both sides by 6 and got the answer to be -6
but when i plug it in 6*-6=-36+9=-27 and u cant sq or cube ruoute negative number am i doing something wronge

6. even if i had a positive 27 the answer still does not come out to be 2 it comes out to be 8 if i di devrything correctly

7. nvm i was squaring it instead of taking the cued root it iwll work if i take the absolute value of -27

8. Originally Posted by imbadatmath
nvm i was squaring it instead of taking the cued root it iwll work if i take the absolute value of -27
Why would you suddenly take an absolute value? If the equation comes up with a -27 then that's what comes up. You can't just change it.

As a matter of fact you can take the cube root of -27. It is -3.

-Dan