If a^2– 4a – 1 = 0 ,a\neq0, then the value of a^2+3a+1/a^2-3/a is

RRB Junior Engineer Stage 1 Model Papers 3

Question : 2 of 100

Marks: +1, -0

a^2– 4a – 1 = 0 ,a≠0

, then the value of

a^2+3a+1/a^2-3/a

Solution:

a^2– 4a – 1 = 0

a^2– 4a = 1

a(a-4)=1

a-4=1/a

a-1/a=4

.....(1)
we have

a^2+3a+1/a^2-3/a

(a^2+1/a^2)+3(a-1/a)

(a-1/a)^2+3(a-1/a)+2

4^2+3×4+2=30

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