Question

已知方程组2x+4y=k x-y=k+3的解xy之间的和为二,求9分之4k的二次方-2k-

Answer 1

2x+4y=k

x-y=k+3

x=(5/6)k+2

y=-(1/6)k-1

x+y=(2/3)k+1=2

k=3/2=1.5

(4k/9)²-2k=-(23/9)