SOLUTION: the cubed root of (2x+3) + 5= 2. I was told the answer is -15, but can't figure out how to get there. This is what I have tried. (2x+3)^3+5^3=2^3. Put both sides to the 3rd

Algebra ->  Radicals -> SOLUTION: the cubed root of (2x+3) + 5= 2. I was told the answer is -15, but can't figure out how to get there. This is what I have tried. (2x+3)^3+5^3=2^3. Put both sides to the 3rd       Log On


   



Question 341839: the cubed root of (2x+3) + 5= 2. I was told the answer is -15, but can't figure out how to get there. This is what I have tried.
(2x+3)^3+5^3=2^3. Put both sides to the 3rd power to undo the cubed root.
8x^3+125=8. Simplified.
8x^3= -117 Subtract 125 from both sides.
x^3= -117/8 Divide both sides by 8.
x^3= -14.625
x= cubed root of (-14.625)
x= i(2.445)
As you can tell I'm doing something totally wrong because I am WAY off.

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
No,no,no.
If a%2Bb=c and you cube both sides, you get %28a%2Bb%29%5E3=c%5E3.
You can't just cube the individual terms, you're missing cross terms.
.
.
.
root%283%2C2x%2B3%29%2B5=2
root%283%2C2x%2B3%29=-3
Now cube both sides,
2x%2B3=-27
2x=-30
highlight%28x=-15%29