Am I correct with this

using (a-b)^2
(sqrt3)^2-2(sqrt3)(5) +(sqrt5)^2
=3-2sqrt15+5
=8-2sqrt15

If you were doing (sqr(3) + sqr(5))^2

yes, you are right.

To verify whether your calculations are correct, let's go step by step:

Using the expression (a-b)^2, you correctly expanded it to (sqrt3)^2 - 2(sqrt3)(5) + (sqrt5)^2.

Now, simplifying each term:

1. (sqrt3)^2 = 3 (The square of the square root of 3 is equal to 3).

2. 2(sqrt3)(5) = 10sqrt3 (The square root of 3 multiplied by 5 is equal to 5sqrt3, then multiplied by 2 is equal to 10sqrt3).

3. (sqrt5)^2 = 5 (The square of the square root of 5 is equal to 5).

Putting the simplified terms together:

Now, we have: 3 - 10sqrt3 + 5 = 8 - 10sqrt3.

Hence, your final answer, 8 - 10sqrt3, is correct.