Question

a)

b)

c)

Answer 1

x+y+2xy=13

x+y-2xy=-3

 

x+2xy=13-y

x[1+2y]=13-y

x=(13-y)/(1+2y)

 

[13-y]/[1-2y]+y-2y[(13-y0/(1-2y)]=-3  /×[1-2y]

13-y+y-2y²-26y+2y²=-3+6y

-26y-6y=-3-13

-32y=-16

y=-16:-32

y=½

x=[13-½]/[1+2×½]=12,5:2=6,25

2]

[3x+y][4-x]=6

[3x+y][2-y]=15

 

3x+y=6/[4-x]

[6/(4-x)(2-y)]=15

12/[4-x]-6y/[4-x]=15

12-6y=60-15x

2-y=10-2,5x

y=2,5-8

 

[3x+y][2-y]=15

6x-3xy+2y-y²=15

6x-3x[2,5x-8]+2[2,5x-8]-[2,5x-8]²=15

6x-7,5x²+24x+5x-16-6,25x²+40x-64=15

-13,75x²+75x-95=0

Δ=b²-4ac=5625-5225=400

Δ=20

x₁=[-b-√Δ]/2a=[-75-20]/-27,5=³⁸/₁₁

x₂=[-b+√Δ]/2a=[-75+20]/-27,5=2

y=2,5x-8

y₁=2,5׳⁸/₁₁-8=⁷/₁₁

y₂=2,5×2-8=-3

3]

trzeciego nie mogę zrobić bo nie dokończone jest 1 równanie układu