A)
{3x+y=5
{2x-y=0
y=5-3x
2x –(5-3x)=0
y=5-3x
2x-5+3x=0
y=5-3x
5x=0+5
y=5-3x
5x=5 /:5
y=5-3x
x=1
y=5-3*1
x=1
y=5-3
x=1
y=2
x=1
b)
{2x-y=5
{x+y=4
2x-y=5
x=4-y
2(4-y)-y=5
x=4-y
8-2y-y=5
x=4-y
-3y=5-8
x=4-y
-3y=-3 /:-3
x=4-y
y=1
x=4-1
y=1
x=3
c)
{-x-y= -6
{-x+y=2
-x=-6+y /:-1
-x+y=2
x=6-y
-6+y+y=2
x=6-y
2y=2+6
x=6-y
2y=8 /:2
x=6-y
y=4
x=6-4
y=4
x=2
y=4
d)
{4x-5y= -4
{-2x+3y=1,1
4x=-4+5y /:4
-2x+3y=1,1
x=-1+1,25y
-2(-1+1,25y) +3y=1,1
x=-1+1,25y
2-2,5y+3y=1,1
x=-1+1,25y
0,5y=1,1-2
x=-1+1,25y
0,5y=-0,9 /:0,5
x=-1+1,25y
y=-1,8
x=-1+1,25*1,8
y=-1,8
x=-1+2,25
y=-1,8
x=1,25
y=-1,8
e)
{-2x+y=0
{3x- 3y=1
y=0+2x
3x-3(0+2x)=1
y=0+2x
3x-6x=1
y=0+2x
-3x=1 /:3
y=0+2x
x=-1/3
y= 2 * -1/3
x=-1/3
y=-2/3
x=-1/3
f)
{3x-2y=0
{2x-5y= -19
3x=2y /:3
2x-5y= -19
X=2/3 y
2(2/3y)-5y=-19
X=2/3 y
4/3y – 5y=-19
X=2/3 y
4. 1/3y = -19
X=2/3 y
y=-4.5/13
x=2/3 *- 4.5/13
y=-4.5/13
x=-2. 12/13
g)
{-4+1,2y= -1
{5x-6y=1,25
1,2y=-1+4
5x-6y=1,25
1,2y=3 /:1,2
5x-6y=1,25
y=2,5
5x-6*2,5=1,25
y=2,5
5x=1,25+15
y=2,5
5x=16,25 /:5
y=2,5
x=3,25
h)
{3x+6(y-2)=0
{x+3y-4=0
3x+6y-12=0
x=4-3y
3(4-3y)+6y=0
x=4-3y
12-9y+6y=0
x=4-3y
-3y=-12 /:-3
x=4-3y
y=4
x=4-3*4
y=4
x=4-12
y=4
x=-8