solve the following systems of linear equations using substation.
Question: 3x+2y=2
x+y+2=0
Help!!!!!Quick,please!!!!
2007-09-23 5:46 pm
回答 (2)
2007-09-23 6:04 pm
✔ 最佳答案
3x+2y=2 ...(1){
x+y+2=0 ...(2)
從(2),
x+y+2=0
x = -2-y ...(3)
把(3)(1)
3(-2-y)+2y=2
-6-3y+2y =2
y =-8
把y=-8代入(2)
x+(-8)+2=0
x-8+2 =0
x =6
參考: me
2007-09-23 9:03 pm
3x + 2y = 2 .... (1)
x + y + 2 = 0 .... (2)
From eq (1). x = -y-2 .... (3)
Substitue (3) into (1)
3(-y-2) + 2y = 2
-3y-6+2y=2
-y=8
y=-8
When y = -8,
x + y + 2 = 0
x -8+2= 0
x= 6
Other easy method,
eq (2) * 3
3x + 3y + 6 = 0 ........ (3)
eq(1) - eq (3)
3x+2y-3x-3y-6 = 2
-y = 8
y = -8
Substitue y = -8 to eq (2)
x - 8 + 2 = 0
x = 6
x + y + 2 = 0 .... (2)
From eq (1). x = -y-2 .... (3)
Substitue (3) into (1)
3(-y-2) + 2y = 2
-3y-6+2y=2
-y=8
y=-8
When y = -8,
x + y + 2 = 0
x -8+2= 0
x= 6
Other easy method,
eq (2) * 3
3x + 3y + 6 = 0 ........ (3)
eq(1) - eq (3)
3x+2y-3x-3y-6 = 2
-y = 8
y = -8
Substitue y = -8 to eq (2)
x - 8 + 2 = 0
x = 6
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