Question

分式与方程组计算的两道题1.已知x＋y=1,求1/2x²＋xy＋1/2y²的值2.已知方程组2x＋y＝1－m 的解x、y

Answer 1

1/2x²＋xy＋1/2y²

=1/2(x²＋2xy＋y²)

=1/2(x+y)²

=1/2*1

=1/2

2:2x＋y＝1－m.(1)

x＋2y=2.(2)

(1)-(2)*2得到

y-4y=1-m-4

y=1+m/3

x=-2m/3

x+y>0

1-m/3>0

m