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回答时间:2024-05-16 14:58
9.解:由已知可得,定义域为,-3<=x<=1,令x=-3+4sina^2,a∈[0,π/2]解释一下,这么做的目的是为的得到定义域,和化简的方便,以及打开根号所以y=根号(1-(-3+4sina^2))+根号(-3+4sina^2+3)y=2cosa+2sina=2根号2sin(a+π/4)由a∈[0,π/2],所以a+π/4∈[π/4,3π/4]所以当a+π/4=π/4或3π/4时,ymin=2当a+π/4=π/2时,ymax=2根号2所以m/M=1/2*根号2
10.log(a)x+log(a)y=log(a)(x*y)=3
a^3=xy
y=a^3/x
a<=x<=2a
1/2a<=1/x<=1/a
所以a^3/2a<=y<=a^3/a
a^2/2<=y<=a^2
y∈[a,a^2]
所以a^2/2=a,a=0,a=2a>1
所以a=2
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