Exams › SSC CGL (Prelims) › General

If 2a + 3b = 10 and ab = 3, find the value of 4a^2 + 9b^2.

1. 60
2. 62
3. 64
4. 66

Correct answer: 64

Solution

Using the identity (2a+3b)^2 = 4a^2 + 12ab + 9b^2: 4a^2 + 9b^2 = (2a+3b)^2 - 12ab = 10^2 - 12(3) = 100 - 36 = 64.

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