Step-by-step explanation: To multiply the square root of 3 times the square root of 21, we simply multiply the numbers that are inside the square roots together.
So, root 21 × root 3 equals root 63.
Next, we simplify the square root of 63. 63 factors as 3 x 21 and 21 factors as 3 x 7. So we have a pair of 3's which means a 3 can come out of the radical and the 7 doesn't pair up stays in the radical so our final answer is [tex]\sqrt[3]{7}[/tex].