题目函数z=xy在条件x+y=1下的极大值为:A. (1)/(4)B. (1)/(2)C. (1)/(3)D. 1函数$z=xy$在条件$x+y=1$下的极大值为:A. $\frac{1}{4}$B. $\frac{1}{2}$C. $\frac{1}{3}$D. $1$题目解答答案A. $\frac{1}{4}$