SSC CGL 2021 PYQ — Question 54

The correct answer is Option 1 i.e -7.

Here it is given that a² + c² + 17 = 2 (a - 8b - 2b²)

On simplifying further one gets,

a² + c²  + 17 = 2a - 16b - 4b² 

(a² - 2a) + (4b² + 16b) + c² + 17 = 0

Now, to simply further one should breakdown 17.

(a² - 2a + 1) + (4b² + 16b + 16) + c² = 0

(a - 1)² + (2b + 4)² + c² = 0

At a = 1, b = -2 and c = 0, L.H.S = R.H.S

Required value of (a³ + b³ + c³) = 1 - 8 + 0 = -7.