Correct Answer - Option 3 : 117
Given:
a2 - b2 = 88
a - b = 4
Formula used:
a2 - b2 = (a - b)(a + b)
Calculation:
a - b = 4 ----(1)
(a - b)(a + b) = 88
⇒ 4 × (a + b) = 88
⇒ a + b = 88/4
⇒ a + b = 22 ----(2)
Adding equation (1) and equation (2), we get
⇒ a - b + a + b = 4 + 22
2a = 26
⇒ a = 13
Put the value of a in equation (2), we get
13 + b = 22
⇒ b = 9
value of ab = 13 × 9
⇒ ab = 117
∴ The value of ab is 117.