SSC CGL 6 Sep 2016 Paper

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Question : 65 of 100

Marks: +1, -0

If a + b = 3, then the value of

a^3 + b^3

+ 9ab – 27 is

24
25
0
27

Solution:

a + b = 3
On cubing both sides,

(a + b)^3

=

3^3

⇒

a^3 + b^3

+ 3ab (a + b) = 27
⇒

a^3 + b^3

+ 3ab × 3 = 27
⇒

a^3 + b^3

+ 9ab – 27 = 0

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