If
the value of
x = 2-√3, then
find
the
value of x²+1/x²
Answers
Answer:
the answer is above
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Answer:
x^2 + 1/x^2 = 14
Step-by-step explanation:
x^2 + 1/ x^2
= ( 2-√3)^ 2 + 1/ ( 2-√3)^2
using the formula : (a-b)^2 = a^2 +b^2 - 2ab
(2-√3)^2 = 4 + 3 - 2 × 2 × √3
x^2 = 7 - 4√3 .
hence :
( 7 - 4√3 ) + 1/ ( 7- 4√3 )
now we have to rationalize 1/ ( 7 - 4√3)
so we have to multiply ( 7 + 4√3 ) to the numerator and denominator
=1 × ( 7 + 4√3 ) / ( 7 - 4√3 ) × ( 7 + 4√3 )
=( 7 + 4√3 ) / ( 7 ) ^2 - ( 4√3 )^2
= ( 7 + 4√3) / 49 - 16 × √3 × √3
= ( 7 + 4√3) / 49 - 16 × 3
= ( 7 + 4√3) / 49 - 48
1 / x^2 = ( 7 + 4√3) .
x^2 + 1 / x^2 = ( 7 - 4√3 ) + ( 7 + 4√3 )
open brackets
= 7 - 4√3 + 7 + 4√3 ( underlined = cancelled )
= 7 + 7
= 14
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