Question

3√21 means how many and why? ​

Answer 1

Answer:

Explanation:

You know that for real, positive numbers you have

√

a

⋅

√

b

=

√

a

⋅

b

This means that you can write

√

3

⋅

√

21

=

√

3

⋅

21

If you write

21

as the product of its prime factors

3

and

7

, you can say that

√

3

⋅

21

=

√

3

⋅

3

⋅

7

=

√

9

⋅

7

Now use the same multiplication property of radicals to write

√

9

⋅

7

=

√

9

⋅

√

7

=

3

⋅

√

7

=

3

√

7