x^2 + 1/25x^2 = 43/5, find (a) 5x + 1/x, (b) 25x^2 - 1/x^2.
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4
Answer:
sorry I am weak in math
so I don't know
Answered by
0
Answer:
Let : x² + ( 1/ 25x² ) = 43/5 ...... (1)
∴ x² + ( 1/ 25x² ) + (2/5) = (43/5) + (2/5)
∴ ( x + 1/ 5x )² = 9
∴ x + ( 1/ 5x ) = ± 3 ................. (2)
∴ from (1) and (2),
... x³ + ( 1/ 125x³)
= x³ + ( 1/ 5x )³
= ( x + 1/ 5x ) [ ( x² + 1/ 25x² ) - (x)(1/ 5x) ]
= ( ± 3 ) [ ( 43/5 ) - ( 1/5 ) ]
= ( ± 3 )( 42/5 )
= ± 126/5
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