Question

perform the indicated operation. assume all variables are positive.
$12\sqrt3{y} + 9\sqrt3{y} = \square$

Explanation:

Step1: Identify like radical terms

Both terms have $\sqrt[3]{y}$ as the radical part.

Step2: Add the coefficients

Add the numerical coefficients of the like radicals.
$12 + 9 = 21$

Step3: Attach the common radical

Multiply the sum of coefficients by the common radical.
$21 \times \sqrt[3]{y}$

Answer:

$21\sqrt[3]{y}$