27^x=67 81^y=603 求证：4y-3x-2=2

来源：学生作业帮编辑：搜狗做题网作业帮分类：数学作业时间：2024/07/24 17:57:45

方法1：
27^x=67 3^3x=67
81^y=603 3^4y=603
603/67
=3^4y/3^3x
=3^(4y-3x)
=9=3^2
4y-3x=2
方法2：27^x=67 x=log(27)67
3x=3log(27)67
=3log(3^3)67
=log(3)67
81^y=603 y=log(81)603
4y=4log(81)603
=4log(3^4)603
=log(3)603
4y-3x
=log(3)603-log(3)67
=log(3)(603/67)
=log(3)9
=2 所以4y-3x=2

x,y属于R*,且x+y=1,求证:(1)(x+1/x)(y+1/y)≥25/4 (2)(x+1/x)^2+(y+1/y 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 (x+y)(x+2y)(x+3y)(x+4y)=-40 3x+5ym+3,2x+3y=2m,求证：4x+7y=6 已知x,y∈R*,x+y=1,求证2/x+1/y≥3+2根号2 3sinX=sin(2X+Y) 求证：tan(X+Y)=2tanX 已知：3sinY=sin(2X+Y),求证tan(X+Y)=2tanX