Question

Rezolvati prin metoda substitutiei sistemele de ecuatii :

Answer 1

Răspuns:

Explicație pas cu pas:

a)

y = 3x - 1

4x - 3y + 7 = 0

4x - 3(3x - 1) + 7 = 0

4x - 9x + 3 + 7 = 0

-5x + 10 = 0

5x = 10

x = 2

y = 6 - 1 = 5

______________

c)

5x + y = 8

7x - 4y = -5

y = 8 - 5x

7x - 4(8 - 5x) = -5

7x - 32 + 20x = -5

27x = 32 - 5 = 27

x = 1

y = 8 - 5 = 3

________________

d)

12x + 9y = 63

4x - y = -3

y = 4x + 3

12x + 9(4x + 3) = 63

12x + 36x + 27 = 63

48x = 63 - 27 = 36

x = 36/48 = 3/4

y = 4*3/4 + 3 = 3 + 3 = 6