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SSC CGL 2019 PYQ — Question 55

SSC CGL - 4th June 2019 - Shift 3 • Quantitative Aptitude • Q55

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If a2 + b2 + 64c2 + 16c + 3 = 2(a + b), then the value of 4a7 + b7 + 8c2 is: 

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Correct answer: C

Explanation

Correct Answer is option 3 i.e. 

Understanding

Application

Given:

a2 + b2 + 64c2 + 16c + 3 = 2(a + b)

a2 + b2 + 64c2 + 16c + 3 = 2(a + b)

⇒ a2 + b2 + (8c)2 + 16c + 3 – 2a – 2b = 0

⇒ a2 – 2a + 1 + b2 – 2b + 1 + (8c)2 + 16c + 1 = 0

⇒ (a – 1)2 + (b – 1)2 + (8c + 1)2 = 0

⇒ a = 1, b = 1 and c = -1/8 

Hence,

4a7 + b7 + 8c2 = 4 × 1 + 1 + 8 × 1/64 =