RRB Group D Model Paper 6 with solutions

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Question : 78 of 99

Marks: +1, -0

If the sum of a/b and its reciprocal is 1 and a ≠ 0, b ≠ 0, then the value of

a^3 + b^3

is

2
-1
0
1

Solution:

(3) Since,

a /b +b/ a

= 1
⇒

a^2+ b^2

= ab
⇒

a^2+ b^2

- ab = 0
Therefore,

a^3+ b^3

= (a + b) (

a^2+ b^2

- ab) = 0

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