Question

3x+2y=2k5x+4y=k+3x+y=-5上头是个方程式,怎样算,有个大括号

Answer 1

3x+2y=2k (1)

5x+4y=k+3 (2)

x+y=-5 (3)

(1)-(3)*2

3x+2y-2x-2y=2k+10

x=2k+10

(2)-(3)*4

5x+4y-4x-4y=k+3+20

x=k+23

所以

k=23-10=13

x=13+23=36

y=-5-x=-41