can someone help me plz...last problem

Question

simplify

(7 + radical (5))(7- radical (5))

for this one i have no idea

(a+b)*(a-b)= a^2 - b^2

memorize that, it is the factors of the difference of squares.

In this case, a=7, b= sqrt5

so, it simplifies to 49-5=44

So , i don't always have to leave it in a radical form for the answers?