Question

A. {2x +3y=1
{1/2x - y=2

B. {3x-y=7
{2x+3y=1

C. {2(x-1)+3(y-2)=5
{3(x+y)-2(x+2)=7

D. {3(x-1)+2(2-y)=5-y
{x+y=2


z góry dziękuję

Answer 1

A. metoda przeciwnych współczynników
{2x+3y=1
{1/2x-y=2|*3

{2x+3y=1
{3/2x-3y=6
____________
7/2 x = 7 | :7/2
x=2
2x+3y=1
2*2+3y=1
4+3y=1
3y=-3|:3
y=-1

{x=2
{y=-1

B.
{3x-y=7|*3
{2x+3y=1

{9x-3y=21
{2x+3y=1
____________
11x=22|:11
x=2
2x+3y=1
4+3y=1
3y=-3|:3
y=-1
{x=2
{y=-1

C.
{2(x-1)+3(y-2)=5
{3(x+y)-2(x+2)=7

{2x-2+3y-6=5
{3x+3y-2x-4=7

{2x+3y=13
{x+3y=11

{2x+3y=13
{x=11-3y

{2*(11-3y)+3y=13
{x=11-3y

{22-6y+3y=13
{x=11-3y

{-3y=-9|:(-3)
{x=11-3y

{y=3
{x=11-3*3

{y=3
{x=2

{x=2
{y=3

D.
{3(x-1)+2(2-y)=5-y
{x+y=2

{3(x-1)+2(2-y)=5-y
{x=2-y

{3x-3+4-2y=5-y
{x=2-y

{3x-y=4
{x=2-y

{3*(2-y)-y=4
{x=2-y

{6-3y-y=4
{x=2-y

{-4y=-2|:(-4)
{x=2-y

{y=1/2
{x=2 - 1/2

{y=1/2
{x=1 1/2