Question

rezolvați prin metoda substituției următoarele sisteme:
va rooogggg repedeee​

Answer 1

Metoda substitutiei: exprimam o necunoscuta in functie de cealalta si o introducem in alta relatie

a)

x+y=10

2x-y=8

x=10-y

2(10-y)-y=8

20-2y-y=8

12=3y

y=4 si x=6

b)

x+y=1

x+2y=-1

x=1-y

1-y+2y=-1

y=-2 si x=3

c)

x-2y=-1

2x-y=7

x=2y-1

2(2y-1)-y=7

4y-2-y=7

3y=9

y=3 si x=5

d)

x+3y=1

2x+y=7

x=1-3y

2(1-3y)+y=7

2-6y+y=7

-5y=5

y=-1

x=4

e)

2x+y=2

x+y=-1

y=2-2x

x+2-2x=-1

-x=-3

x=3 si y=-4

f)

x+y=2

2x+y=1

x=2-y

2(2-y)+y=1

4-2y+y=1

y=3 si x=-1

g)

x+4y=7

2x-y=-4

x=7-4y

2(7-4y)-y=-4

14-8y-y=-4

9y=18

y=2 si x=-1

h)

2x+y=0

3x-2y=-1

y=-2x

3x-2(-2x)=-1

3x+4x=-1

7x=-1

$x=-\frac{1}{7} \\\\y=\frac{2}{7}$

Un alt exercitiu gasesti aici: https://brainly.ro/tema/2688828

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