Question

A poder ser por el método de sustitución :(​

Answer 1

1.

3x + 5y = 20

2(x - 5y) = 0

Despeja x en la ec1

x = 20/3 - 5/3y

Sustituye en la ec2

2(20/3 - 5/3y - 5y) = 0

40/3 - 10/3y - 10y = 0

-40/3y = -40/3

y = 1

Sustituye en la ec1

3x + 5(1) = 20

3x + 5 = 20

3x = 15

x = 5

2.

3/4x + y/3 = 4

2x - y/6 = 15/2

Despeja x en la ec2

2x = 15/2 + y/6

x = 15/4 + y/12

Sustituye en la ec1

3/4(15/4 + y/12) + y/3 = 4

45/16 + 3/48y + y/3 = 4

19/48y = 4 - 45/16

19/48y = 19/16

y = 3

Sustituye en la ec 2

2x - 3/6 = 15/2

2x = 15/2 + 3/6

2x = 8

x = 4