f(x)=(log2 x-log2 2log2 4)=(log2 x-1)*(log2 x-2)=(log2 x)²-3log2 x+3=(log2 x-3/2)²+3/4
由此可知这是一个复合函数,单调性复合同增异减的原则,又因为x∈[根号2,8],所以可知当x∈[0,2*根号2]时单调递减,当x∈(2*根号2,8]时单调递增,所以当log2 x=3/2(即x=根号8)时取最最小值3/4,当x=8时取最大值3
f(x)=(log2 x-log2 2log2 4)=(log2 x-1)*(log2 x-2)=(log2 x)²-3log2 x+3=(log2 x-3/2)²+3/4
由此可知这是一个复合函数,单调性复合同增异减的原则,又因为x∈[根号2,8],所以可知当x∈[0,2*根号2]时单调递减,当x∈(2*根号2,8]时单调递增,所以当log2 x=3/2(即x=根号8)时取最最小值3/4,当x=8时取最大值3