a)8x-y=2/*4
5x+4y=1
32x-4y=8
5x +4y=1} dpdajemy pierwsze równanie do drugiego
32x+5x-4y+4y=8+1
37x=9/:37
x=9/37 wstawiamy do drugiego
5*9/37+4y=1
4y=1-45/37=-8/37
4y=-8/37/:4
y=-2/37
b)6x-y=63/*3
4x+3y=28
18x -3y=189
4x+3y=28 dodajemy obustronnie
18x+4x-3y+3y=189+28
22x=217/:22
x= 217/22
-y=63-6*217/22
-y=63-651/11
-y=(693-651)/11 = 42/11
y=-42/11
c)12x+15y=8/:3
16x+9y=7/:(-4)
4x+5y=8/3
-4x-9/4y=-7/4 dodajemy obustronnie
4x-4x+5y-9/4y=3-7/4
11/4y=5/4/:11/4
y= 5/11
12x +15*5/11=8
12x=8-75/11=13/11/:12
x=13/132
d)x+4y=12/*(-1)
x+1/8y=4
-x-4y=-12
x+1/8y=4
-x+x-4y+1/8y=-12+4
-31/8y=-8/*(-8/31)
y=64/31
x=12-4*64/31=12-256/31=12- 8 8/31= 3 23/31
e)-8x+2y=13
3x-y=6/*2
-8x+2y=13
6x-2y=12
-8x+6x+2y-2y=12+13
-2x=25/:(-2)
x= - 25/2
-y=6-3*(-25/2) = 6+37 1/2= 43 1/2
y= - 43 1/2
f) 9/2x-3y=48
3/2x+y=11/*3
9/2x +9/2x-3y+3y=48+33
9x = 81/:9
x=9
y=11- 3/2*9 = 11-13 1/2 = -2 1/2
