Question

For the following system, use the second equation to make a substitution for y in the first equation.

3x + y = 1
y + 4 = 5x

What is the resulting equation?

3x + 5x - 4 = 1
3x + 4 - 5x = 1
3x + 5x + 4

Answer 1

3x + y = 1

y + 4 = 5x

Firstly we use the second equation to solve for y , that is we isolate y on left side

y+4 = 5x

subtract 4 from both sides

y = 5x -4

Now we substitute the value of y in first equation

so we get

3x + 5x-4 = 1

If we want we can further solve it for x

8x -4 = 1

add 4 to both sides

8x = 5

divide both sides by 8

x= 5/8