问题标题:
高一数学问题,大神请进~O(∩_∩)O~设ab为不等于1的正数,并且实数x,y,z满足关系式1/x+1/y=1/z。求证:(1)若a的x次方=b的y次方,则a的x次方=(ab)的z次方;(2)若a的x次方=(ab)的z次方,
问题描述:
高一数学问题,大神请进~O(∩_∩)O~
设ab为不等于1的正数,并且实数x,y,z满足关系式1/x+1/y=1/z。求证:
(1)若a的x次方=b的y次方,则a的x次方=(ab)的z次方;
(2)若a的x次方=(ab)的z次方,则b的y次方=(ab)的z次方
跪求详细步骤,做这类题目需要怎么样的思路?
房韡回答:
Becausea^x=b^y,b=a^(x/y),
Alsoas1/x+1/y=1/z,z=1/(1/x+1/y)=xy/(x+y)
Then(ab)^z=(a*a^(x/y))^[xy/(x+y)]=a^[(1+x/y)*xy/(x+y)]=a^[(x+y)/x*xy/(x+y)]=a^x
Soa^x=(ab)^z.
Asa^x=(ab)^z
Thena^x=(ab)^[xy/(x+y)]
Soa=(ab)^[y/(x+y)],whichleadstoa^(x+y)=(ab)^y,thena^x*a^y=a^y*b^y,
Thenwehave a^x=b^y.
Recallinga^x=(ab)^zgiveninthecondition,wehaveprovenb^y=(ab)^z.
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