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SSC CGL 2022 PYQ — Question 67

SSC CGL - 02 Dec 2022 - Shift 2 • Quantitative Aptitude • Q67

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If a + b = 5 and ab = 6, then find 3(a2 + b2).

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Correct answer: A

Explanation

The correct answer is Option 1. i.e. 39.

Given:

a + b = 5

ab = 6    ....(i)

Concept Used:

(a + b)2 = a2 + 2ab + b2    ....(ii)

Explanation:

Using equation (ii), we get

(a + b)2 = 52

⇒ a2 + 2ab + b2 = 25

⇒ a2 + b2 + 2(6) = 25

⇒ a2 + b2 = 13

Now, the required value is 3(a2 + b2) = 3(13) = 39

Hence the required value is 39.