搜搜考试网log2(x y)=log2x log2y则x-1分之4x
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我大致说一下（里面是个完全平方式+2XY在减一个2XY凑一个完全平方式子）已知X+2Y=1这个条件这么简单还有脸问
(1)y=log2(x^2)-log2(x)=2log2(x)-log2(x)=log2(x)y'=1/(xln2)(2)y=-2sin(x/2)(-cos(x/2)).余弦二倍角公式=2sin(x/
令x=2^log2^(-3)则log2(x)=log2(-3)X=-3
因为x=1-2y>=0,所以0
t是增函数,所以t的最大值就是y^2+2xy+1取得最大值时候.因为X=1-2y,所以y^2+2xy+1=-3y^+2y+1.f（x）=-3y^+2y+1令f（x）的导数=0则-6y+2=0得到y=1
log(2)5+log(2)1/10=log(2)(5×(1/10))=log(2)2=1
log2(0.5)=log2(1/2)=log2{2ˆ(-1)}=-1log4(0.5)=log2²(0.5)=1/2log2(0.5)=-1/2-log2(0.5)=1log2(
log2^x=log4^9=log2^2(3^2)=log2^3所以x=3
如果log4(log2^x)是表示外面的log以4为底,而里面的log以10或其它数(>0)为底的话,则log4(log2^x)=[log2(log2^x)]/2=log2(log4^x)=log2(
方法一(log89/log23)=(lg9/lg8)/(lg3/lg2)=(2lg3/3lg2)/(lg3/lg2)=(2/3)*(lg3/lg2)/(lg3/lg2)=2/3方法二(log89/lo
log1/2(log2x)=1--->log2x=1/2-->x=2^(1/2)log1/3(log3y)=1--->log3y=1/3-->y=3^(1/3)x^6=8再问：x^6=8
log2（15x+15y+16）=log2x+log2y+2=log2x+log2y+log24=log2(4xy)15x+15y+16=4xy15(x+y)=4xy-16x、y都是真数,x>0,y>
y=lnx/ln2∴y‘=1/(xln2)
log2(2-x)=log2(x-1)+log(2)log2(2-x)=log2[2(x-1)]2-x=2x-2x=4/3带入检验,成立所以x=4/3
[log2(-x)]2-log2((-x)2)>=0so[log2(-x)]2-2*log2(-x)>=0solog2(-x)>=2orlog2(-x)=2,-x>=4,x
没有错...换底公式的运用于逆运用.log(2)(3)xlog(3)(7)=ln3xln7/ln2xln3=ln7/ln2=log(2)(7)
log(2,9)=log(2,3^2)=2log(2,3)log(2,8)=log(2,2^3)=3log(2,2)=3所以(log2,9)/(log2,8)=2/3(log2,3)
log2(a1a2*……*a2009)=2009a1a2*……*a2009=2^2009a1a2009=a2a2008=……=a1004a1006=(a1005)²所以a1a2*……*a20
log2(x+3)+log2(x+2)=1log2{(x+3)*(x+2)}=1(x+3)*(x+2)=2x^2+5x+4=0(x+4)(x+1)=0所以x=-4或-1因为x+3>0x+2>0所以x>
时,y有最小值为-1/4当t=3即x=8时,y有最大值为2.参考资料：我教高一数学.y=log2(x/4)*log2(x/20=log2(3x/