43. If (a+1/a)*2 =3 , then a*39+a*21-a*27-a*9+1=?
- a° +1=? ( a>0)
a. 0
b.1
c.-1
d.-2
Answers
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2
Answer:
a+(1/a) = 3^(1/2)
Cube both sides.
a^3 + (1/a)^3 = 0
so, a^6 = -1
That means, a^3 = i
a^39 = i^13 = i
a^21 = i^7 = -i
a^27 = i^9 = i
a^9 = i^3 = -i
So, i - i - i + i + 1 = 1
Final answer : 1
Step-by-step explanation:
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