已知2log3[(x-y)/2]=log3(xy),则x/y=?
写下过程,谢谢
已知2log3[(x-y)/2]=log3(xy),则x/y=?
写下过程,谢谢
有等式可得
[(x-y)/2]的平方=x乘以y
化简就行了
∵2log3[(x-y)/2]=log3(xy),
∴log3[(x-y)/2]²=log3(xy),
故[(x-y)/2]²=xy
(x-y)²=4xy
x²-6xy+y²=0
(x/y)²-6(x/y)+1=0
( x/y-3)²=8
x/y=3±2√2
而由题意得 x>y ,即x/y>1
∴x/y=3+2√2