Question

select the correct answer.
which expression is equivalent to $21\sqrt3{15} - 9\sqrt3{15}$?
a. 12
b. $30\sqrt3{15}$
c. $12\sqrt3{5}$
d. $12\sqrt3{15}$

Explanation:

Step1: Factor out common term

Identify $\sqrt[3]{15}$ as the common factor:
$21\sqrt[3]{15} - 9\sqrt[3]{15} = (21 - 9)\sqrt[3]{15}$

Step2: Subtract coefficients

Calculate the difference of the coefficients:
$21 - 9 = 12$

Step3: Combine results

Multiply the result with the common radical term:
$12\sqrt[3]{15}$

Answer:

D. $12\sqrt[3]{15}$