你答的当X=1984,Y=1916时,计算:(X的四次方-Y的四次方/X的二次方-2XY=Y的二次方)×(Y-X/X中用计算器算为390怎么回事啊
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你答的当X=1984,Y=1916时,计算:(X的四次方-Y的四次方/X的二次方-2XY=Y的二次方)×(Y-X/X中用计算器算为390怎么回事啊
你答的当X=1984,Y=1916时,计算:(X的四次方-Y的四次方/X的二次方-2XY=Y的二次方)×(Y-X/X中用计算器算为390
怎么回事啊
你答的当X=1984,Y=1916时,计算:(X的四次方-Y的四次方/X的二次方-2XY=Y的二次方)×(Y-X/X中用计算器算为390怎么回事啊
(X^4-Y^4)/(X²-2XY+Y²) × (Y-X)/(X²+Y²)
=(X²+Y²)(X²-Y²)/(X-Y)² × (Y-X)/(X²+Y²)
=(X²+Y²)(X-Y)(X+Y)/(X-Y)² × [-(X-Y)/(X²+Y²)]
=(X+Y)/(X-Y) × [-(X-Y)]
=-X-Y
=-1984-1916
=-3900
如果用计算器,那么带入
=(15494111297536-13476652155136)/4624 × (-68)/(3936256+3671056)
=2017459142400/4624 × (-68)/7607312
最后算出来也是-3899.9923100……
计算器有点出入的,小数不会约分,可能你哪里按错了.
有什么不懂的可以追问、
(X^4-Y^4)/(X²-2XY+Y²) × (Y-X)/(X²+Y²)
=(X²+Y²)(X²-Y²)/(X-Y)² × (Y-X)/(X²+Y²)
=(X²+Y²)(X-Y)(X+Y)/(X-Y)² × [-(X-Y)/(X²+Y²)]
=(X+Y)/(X-Y) × [-(X-Y)]
=-X-Y
=-1984-1916
=-3900