Question

Y = 3x + 4y, x + 2y = -1 using substitution

Answer 1

The answers should be x=1 and y=-1

Answer 2

x = 1

y = -1

Explanation:

y = 3x + 4y

3x + 3y = 0

So, we have 2 equations that are

3x + 3y = 0

x + 2y = -1

Times the second equation by -3

3x + 3y = 0

-3x - 6y = 3

-3y = 3

y = -1

Now put -1 in for y and solve for x

x + 2(-1) = -1

x - 2 = -1

x = 1

Let's check

1 + 2(-1) = -1

1 - 2 = -1

-1 = -1

So, x = 1 and y = -1 is the correct answer.