分式计算题目一道已知x+y=4,xy=3,分别求下列各式的值 (1) 1/x+1/y (2)1/x^2+1/y^2

分式计算题目一道已知x+y=4,xy=3,分别求下列各式的值 (1) 1/x+1/y (2)1/x^2+1/y^2
分式计算题目一道
已知x+y=4,xy=3,分别求下列各式的值 (1) 1/x+1/y (2)1/x^2+1/y^2

分式计算题目一道已知x+y=4,xy=3,分别求下列各式的值 (1) 1/x+1/y (2)1/x^2+1/y^2
1/x+1/y
=(x+y)/xy
=4/3
1/x^2+1/y^2
=(1/x+1/y)^2-2/xy
=16/9-2/3
=16/9-6/9
=10/9