SSC CGL 7 Sep 2016 Paper

Question : 63 of 100

Marks: +1, -0

If a – b = 1 and

a^3 – b^3

= 61, then the value of ab will be

Solution:

a^3 – b^3

(a – b)^3

+ 3ab (a – b)
⇒ 61 = 1 + 3ab × 1
⇒ 61 – 1 = 3ab = 60
⇒ ab =

{60}/3

= 20

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