Question

Zrobił by ktoś te przykłady z układu równań ? (metoda podstawiania)

Answer 1

Zadanie 53
5x + 4y + 18 = 0
2x + 3y + 10 = 0

5x + 4y = - 18
2x + 3y = - 10         /:2

5x + 4y = - 18
x = - 5 - 1.5y

5(-5-1.5y) + 4y = - 18
x = - 5 - 1.5y 

-25 - 7.5y + 4y = - 18
x = -5 - 1.5y 

-3.5y = 7
x = - 5 - 1.5y 

y = -2
x = -5 - 1.5*(*-2)

y = -2
x = - 2

zadanie 54
3x + 7y + 8 = 0
5x + 6y + 31 = 0       /:5

3x + 7y = - 8
x = - 6.2 - 1.2y 

3(-6.2-1.2y)+7y= - 8
x = -6.2 - 1.2y 

- 18.6 - 3.6y + 7y= - 8
x = -6.2 - 1.2y

3.4y = 10.6
x = -6.2 - 1.2y 

y = 53/17
x = -6.2 - 1.2*53/17

y = 53/17
x = - 169/17

zadanie 55
3x + 2y + 9 = 0
2x + 3y + 1 = 0     /:2

3x + 2y = - 9
x = - 0.5 - 1.5y

3(-0.5-1.5y)+2y= -9
x= -0.5 - 1.5y

-1.5 - 4.5y + 2y = -9
x = -0.5-1.5y

-2.5y = -7.5
x = -0.5 - 1.5y

y = 3
x = -0.5 - 1.5*3

y = 3
x = - 5