Question

若K使方程组3X+5Y=K+2 2X+3Y=K的解XY的和为2求X．Y．K的值

Answer 1

3X+5Y=K+2 (1)

2X+3Y=K (2)

(1)-(2)*2

3X+5Y-4X-6Y=K+2-2K

-X-Y=2-K

X+Y=K-2

X+Y=2

K-2=2

K=4

2X+3Y=K=4

X+Y=2

2X+2Y=4

Y=0,X=2