2X-4Y=6 (1)
3X+2Y=17 (2)
(1)+(2)*2
2X+3X*2-4Y+2Y*2=6+17*2
8X=40
X=5
Y=6-2*5/(-4)=1
3Y=X+5 (1)
2X+5X=23 (2) (題目可能有誤,應(yīng)2X+5Y=23)
(1)整理,
X-3Y=-5 (3)
(2)-(3)*2
2X-2X+5X-(-3Y)*2=23-2*(-5)
11Y=33
Y=3
X=3*3-5=4
2X+3X=7 (1) (題目可能有誤,應(yīng)是2X+3Y=7)
3X-5Y=1 (2)
(1)*3-(2)*2
2X*3-3X*2+3Y*3-(-5Y)*2=7*3-1*2
19Y=19
Y=1
X=(1+5*1)/3=2
3X+5Y=5 (1)
3X-4Y=23 (2)
(1)-(2)
3X-3X+5Y-(-4Y)=5-23
9Y=-18
Y*-2
X=[5-5*(-2)]/3=5
X=3Y (1)
2X-Y=5 (2)
(1)代入(2)
2*(3Y)-Y=5
Y=1
X=3
3X+Y=1 (1)
X/2+Y/4=0 (2)
(2)*4得
2X+Y=0 (3)
(1)-(3)
3X-2X+Y-Y=1-0
X=1
Y=1-3*1=-2
已知X=2是方程MX-Y=1的解,求M和N的值
Y=1 X-NY=7
將X=2代入方程MX-Y=1
M*2-Y=1
當(dāng)Y=1時(shí),M*2-1=1,則M=1
X-NY=7,則
N=(X-7)/Y=(2-7)/1=-5