<p><a href="https://www.prepswift.com/quizzes/quiz/prepswift-substitution-method" target="_blank">Substitution Method Exercise</a></p>
<p><strong>Note</strong>: about 1 minute and 25 seconds into the video, Greg says that 8x = 32 is divided by 4 on both sides to get x = 4. He's actually dividing by 8.</p><p>One way to solve a system of equations is to use the <span style="color:#27ae60;">Substitution Method</span>. In this approach, you isolate one of the variables in one of the equations and then plug what it is equated to into the other equation. See the example below for how it works:</p>
<p>$$5x-3y=-1$$</p>
<p>$$y= -4x + 6$$</p>
<p style="margin-left: 40px;">Notice in the second equation that $y$ is isolated and we know that it equals $-4x+6$. We can plug that value of $y$ into the first equation.</p>
<p>$$5x-3(-4x+6)=-1$$</p>
<p style="margin-left: 40px;">We then solve for $x$, which then allows us to solve for $y$ in either or both of the original equations.</p>
<p>$$5x+12x-18=-1$$</p>
<p>$$17x=-17$$</p>
<p>$$x=1$$</p>
<p style="margin-left: 40px;">We can easily use that $x=1$ value to find out that $y=2$.</p>