Question

The product of (5+3√2) (5-3√2) is

Answer 1

7

Explanation:

First use the (a-b) and (a+b) = a^2 - b^2 which is equal to 25 - 9 x 2

then you multiply 9 x 2 which is 18 so 25 - 18 thus 7. The trick is to remember the rules.