Question

Solve each system by substitution. Show all work.

y = -3x
y= x-4

Answer 1

since y = - 3x and y = x - 4

we have

- 3x = x - 4

4x = 4

x = 1

and then y = - 3 * 1 = - 3

(1 ; - 3)

Answer 2

(1,-3)

Explanation:

y = -3x

y= x-4

Substitute -3x for y in the second equation

-3x = x-4

Subtract x from each side

-3x-x = x-4-x

-4x = -4

Divide each side by -4

-4x/-4 = -4/-4

x=1

Now we can find y

y = x-4

y = 1-4

y= -3

(1,-3)