Add or subtract. Assume all variables represent positive real numbers.
-$$12 \sqrt [ 3 ] { 3 } + 9 \sqrt [ 3 ] { 3 }$$
A) $21 \sqrt [ 3 ] { 6 }$
B) $- 3 \sqrt [ 3 ] { 3 }$
C) $21 \sqrt [ 3 ] { 3 }$
D) $21 \sqrt [ 3 ] { 9 }$

Question

Quizplus · Accepted Answer

When adding or subtracting terms with radicals, you can only combine like terms. Since both terms are $\sqrt[3]{3}$, you can add their coefficients: $12 + 9 = 21$, resulting in $21\sqrt[3]{3}$.

Add or Subtract 1233+93312 \sqrt [ 3 ] { 3 } + 9 \sqrt [ 3 ] { 3 }1233​+933​

Add or Subtract $12 \sqrt [ 3 ] { 3 } + 9 \sqrt [ 3 ] { 3 }$