Final answer:
Sunil used the difference of squares identity to solve the expression (√5 + √7)(√5 − √7), resulting in a value of -2.
Step-by-step explanation:
Sunil is applying the algebraic identity (a+b)(a-b) = a² - b² to solve the expression (√5 + √7)(√5 − √7). Here's how it works:
- Following the identity (a+b)(a-b) = a² - b², set a equal to √5 and b equal to √7.
- When you square a, you get 5 (since (√5)² = 5). Similarly, squaring b gives 7 (since (√7)² = 7).
- Last, subtract the square of √7 from the square of √5 to get (5-7) which equals -2.
So, (√5 + √7)(√5 − √7) = -2 according to the identity used.
Learn more about Difference of Squares Identity