Question

a^2 + 1/a^2 = 20 , so a + 1/a ?
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Answer 1

Answer:

_____________________________

Answer 2

Answer:

If a, b, c are in AP then 2b=a+c

So,

2(a

2

+a+1)=3a

2

−3a+3+2a+1

2a

2

+2a+2=3a

2

−a+4

⇒3a

2

−2a

2

−a−2+4−2=0

⇒a

2

−3a+2=0

⇒a

2

−2a−a+2=0

⇒a(a−2)−1(a−2)=0

So (a−1)(a−2)=0

So a=1 or a=2.