(√7+√5)(√7-√5)

Answer 1

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

( square root 7 + square root 5 ) ( square root 7 - square root 5 ) =

( square root 7 ) ^ 2 - ( square root 5 ) ^ 2 = 7 - 5 = 2