Question

DAU 100 DE PUNCTE!!! Imi trebuie exercitiile astea pana maine
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Answer 1

Răspuns:

a. {4×(2x+3y-5)=3×(5x-2y+9)

{3×(4x+2y+10)=5×(3x-y+12)

{8x+12y-20=15x-6y+27

{12x+6y+30=15x-5y+60

{8x+12y-15x+6y=27+20

{12x+6y-15x+5y=60-30

{8x-15x+12y+6y=47

{12x-15x+6y+5y=30

{-7x+18y=47/×11

{-3x+11y=30/×18

{-77x+198y=517

{-54x+198y=540

----------------------- (-)

-77×-(-54x) - 198y-198y=517-540

-77x+54× /=-23

23x=23/÷23

x=1

-3×1+11y=30

-3+11y=30/+3

11y=33/÷11

y=3

b.{5(x+2y-1)=3(2x-4y+5)

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

{5x+10y-5=6x-12y-15

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

{5x+10y+12y-6x=-15+5

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

{5x-6x+10y+12y=-10

{4x-6x+6y-3y=-1

{-1x+22y=-10/×2

{-2x+3y=-1

{-2x+44y=-40

{-2x+3y=-1

---------------- (+)

-2x+(-2x)+44y+3y=-40+(-1)

-2x+2x+47y=-40+1

/ 47y=39

y=1,2

-2x+3×1,2=-1

-2x+3,6=-1/-3,6

-2x=-4,6/÷(-2)

x=2,3

c. prima fractie o amplifici cu 6, iar pe a doua cu 3 si va veni asa

{2x+y-1+x+y+1=3

aici amplifici la prima cu 3 iar la celelalte două cu 1

{x-5-2x-y-3=7

{2x+y+x+y=3-1+1

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

{2x+x+y+y=3

{-x-y=15

{3x+2y=3

{-x-y=15/×3

{3x+2y=3

{-3x-3y=45

---------------- (+)

3x+(-3x)+2y+3y=3+45

/ 6y=48/÷6

y=8

3x+2×8=3

3×+16=3/-16

3x=-13/÷3

x=-39

d.{3(3x-y+2)=5(4x-2y-6)

{5(4x+y+2)=4(3x+2y+8)

{9x-3y+6=20x-10y-30

{20x+5y+10=12x+8y+32

{9x-3y+10y-20x=-30-6

{20x+5y-8y-12x=32-10

{9x-20x-3y+10y=-36

{20x-12x+5y-8y=22

{-11x-7y=-36/×3

{8x+3y=22/×7

{-33x-21y=-108

{56x+21y=154

-------------------- (+)

-33x+56x-21+21y=-108+154

23x /= 46/÷23

x=2

8×2+3y=22

16+3y=22

3y=22-16

3y=6/÷3

y=2