Question

Solve by substitution: y = 3x + 4 and y = -2x – 1.

Answer 1

we have two equation and two variables:

`\begin{gathered} y=3x+4 \\ y=-2x-1 \end{gathered}`

Now we can substitude the first equation into the second equation:

`3x+4=-2x-1`

Now we move all the terms with an x to the left and the constants to the right

`3x+2x=-1-4`

and we simplify

`\begin{gathered} 5x=-5 \\ x=-(5)/(5) \\ x=-1 \end{gathered}`

Now with the value of x, we can substitude into any equation, I am going to use the first one:

`\begin{gathered} y=3x+4 \\ y=3(-1)+4 \\ y=-3+4 \\ y=1 \end{gathered}`