SSC Selection Post 2022 PYQ — Question 74

SSC Selection Post - Matriculation Level 2022 - 7 Feb 2022 - Shift 3 • Quantitative Aptitude • Q74

If a + b + 2 and ab + 4, then find the value of a4 + b4 + ab3 + ba3.

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e. -32.

a + b = 23

Squaring both sides

⇒ (a + b)2 = 22

⇒ a2 + b2 + 2ab = 4

⇒ a2 + b2 = 4 - 8 = -4

Squaring both sides

⇒ (a2 + b2)2 = (-4)2

⇒ a4 + b4 + 2a2b2 = 16

⇒ a4 + b4 = 16 - 32

⇒ a4 + b4 = -16

⇒ a4 + b4 + ab3 + ba3 = a4 + b4 + ab(b2 + a2)

⇒ -16 + 4 × -4 = - 16 - 16 = -32