SOLUTION: ok so the problem ask "add or subtract as the signs indicate. When possible, check results with the calculator, recording screen displays exactly as they apprear" here is the probl

Algebra ->  Square-cubic-other-roots -> SOLUTION: ok so the problem ask "add or subtract as the signs indicate. When possible, check results with the calculator, recording screen displays exactly as they apprear" here is the probl      Log On


   



Question 237777: ok so the problem ask "add or subtract as the signs indicate. When possible, check results with the calculator, recording screen displays exactly as they apprear" here is the problem
3cubed root of 27 + 12 cubed root of 216.
so far all i have done is 3 cubed root of 3 squared times 2. then i got stuck. i dont even know if this is even right

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
3cubed root of 27 + 12 cubed root of 216.
:
I am going to use 3sqrt%28n%29 as a symbol for cube root
:
3%2A3sqrt%2827%29+%2B+12%2A3sqrt%28216%29
You know the cube root of 27 is 3: (3*3*3=27)
3%2A3+%2B+12%2A3sqrt%28216%29
:
Factor 216 to reveal some perfect cubes inside the radical 8 * 27 which are 2^3 & 3^3
9+%2B+12%2A3sqrt%288%2A27%29
extract the perfect cubes, gets rid of the radical
9 + 12*2*3
9 + 72 = 81
:
to check on a calc use the exponent equiv of cube root ^(1/3)
:
Enter:3*27^(1/3) + 12*216^(1/3) results in 81; confirms your solutions