x cube + 1 by 125xcube if x square + 1 by 25 x square. = 8 whole 3 by 5
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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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