Question

Resolver los siguientes ejercicios de ecuación lineal 2x2 por método de sustitucion

A) 5x+2y=2
- 3x+3y=5

B) 5x-2y=2
X+3y=2

C) 5x-y=3
- 2x+4y= - 12

Answer 1

A)
5x + 2y = 2
2y = 2 - 5x
y = (2 - 5x)/2

-3x + 3y = 5
-3x + 3(2 - 5x)/2 = 5
-6x + 3(2 - 5x) = 10
-6x + 6 - 15 x = 10
-21x = 4
x = -4/21

y = (2 - 5(-4/21))/2
y = (2 + 20/21)/2
y = 1 + 10/21
y = 31/21 

B)
5x - 2y = 2
5x = 2 + 2y
x = (2 + 2y)/5

x + 3y = 2
(2 + 2y)/5 + 3y = 2
2 + 2y + 15y = 10
2 + 17y = 10
17y = 8
y = 8/17

x = (2 + 2(8/17))/5
x = (2 + 16/17)/5
x = (50/17)/5
x = 10/17

C)
5x - y = 3
5x - 3 = y

-2x + 4y = -12
-2x + 4(4x - 3) = -12
-2x + 16x - 12 = -12
14x = 0
x = 0

y = 5*0 - 3
y = -3