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CAT 2005 — QA Question 26

Square root of SurdsEasy
Passage / Data

Answer the next 2 questions based on the information given below.

Ram and Shyam run a race between points A and B, 5 km apart. Ram starts at 9 a.m. from A at a speed of 5 km/hr, reaches B, and returns to A at the same speed. Shyam starts at 9:45 a.m. from A at  a speed of 10 km/hr, reaches B and comes back to A at the same speed.

Let x = 4+4-4+4-....to infinity. Then x equals

Answer & solution

  • A

    3

  • B

    (13-12)

  • (13+12)

  • D

    13

Solution

x = 4+4-4+4-....to infinity

∴ x2 - 4 = 4-4+4-.... to infinity

∴ (x2 - 4)2 - 4 = - 4+4-...to infinity

∴ (x2 - 4)2 - 4 = - x

Now, substituting options, we find that only option (c) satisfies the above equation.

Hence, option (c).

CAT 2005 QA Q26: Let x = 4 + 4 - 4 + 4 - . . . . t o i n f i n i t y . Then x equals — Solution | TheCATExam