a) {6(x+y)=10yy−x=0.5 ∣+x
{6x+6y=10y ∣−6yy=0.5+x
{6x=4yy=0.5+x
{6x=4(0.5+x)y=0.5+x
{6x=2+4x ∣−4xy=0.5+x
{2x=2 ∣:2y=0.5+x
{x=1y=0.5+1=1.5
b) {10(y+2)+3(x−5)=x−525(y+2)+3(x−5)=−10 b) {10(y+2)+3(x−5)=x−525(y+2)+3(x−5)=−10
{10y+20+3x−15=x−525y+50+3x−15=−10
{10y+3x+5=x−5 ∣−x25y+3x+35=−10 ∣−35
{10y+2x+5=−5 ∣−525y+3x=−45
{10y+2x=−10 ∣⋅(−5)25y+3x=−45 ∣⋅2
{−50y−10x=5050y+6x=−90 ∣+
−4x=−40 ∣:(−4)
x=10
Wstawiamy wyliczoną wartosˊcˊ x do drugiego roˊwnania ostatniego układu roˊwnanˊ:
50y+6⋅10=−90 ∣−60
50y=−150 ∣:50
y=−3
{x=10y=−3
c) {2(2x−y)+3(x+3y)=425(x+3y)−8(2x−y)=−32
{4x−2y+3x+9y=425x+15y−16x+8y=−32
{7x+7y=42 ∣:7−11x+23y=−32
{x+y=6 ∣−y−11x+23y=−32
{x=6−y−11(6−y)+23y=−32
{x=6−y−66+11y+23y=−32
{x=6−y−66+34y=−32 ∣+66
{x=6−y34y=34 ∣:34
{x=6−1=5y=1
d) {2y+4x−51(x+2)=1.1 ∣⋅20x−2y+4=2x+43(y−0.5) ∣⋅4
{10y+5x−4(x+2)=224x−8y+16=2x+3(y−0.5)
{10y+5x−4x−8=22 ∣+84x−8y+16=2x+3y−1.5 ∣−2x−3y−16
{10y+x=30 ∣−10y2x−11y=−17.5
{x=30−10y2(30−10y)−11y=−17.5
{x=30−10y60−20y−11y=−17.5
{x=30−10y60−31y=−17.5 ∣−60
{x=30−10y−31y=−77.5 ∣:(−31)
{x=30−10yy=2.5
{x=30−10⋅2.5=5y=2.5