Glossary Checklist FAQ

 Warm Up

Solving Equations


Solve for \(x\) in the following equations. Check your answers.

  1. \(3x + 4 = 16\)

    \[\begin{align}
     3x + 4 &= 16 \\
     3x + 4 - 4 &= 16 - 4 \\
     3x &= 12 \\
     \frac{{3x}}{3} &= \frac{{12}}{3} \\
     x &= 4  \end{align}\]

    Check:

    \(\begin{align}
     3x + 4 &= 16 \\
     3\left( 4 \right) + 4 &= 16 \\
     12 + 4 &= 16 \\
     16 &= 16 \\
     \end{align}\)
  2. \(5x^2 + 6 = 86\)

    \[\begin{align}
     5x^2 + 6 &= 86 \\
     5x^2 + 6 - 6 &= 86 - 6 \\
     5x^2 &= 80 \\
     \frac{{5x^2 }}{5} &= \frac{{80}}{5} \\
     x^2 &= 16 \\
     \sqrt {x^2 } &= \pm \sqrt {16}  \\
     x &= \pm 4 \\
     \end{align}\]

    Check:

    \(x = 4\)
    \(\begin{align}
     5x^2 + 6 &= 86 \\
     5\left( 4 \right)^2 + 6 &= 86 \\
     5\left( {16} \right) + 6 &= 86 \\
     80 + 6 &= 86 \\
     86 &= 86  \end{align}\)
    \(x = -4\)
    \(\begin{align}
     5x^2 + 6 &= 86 \\
     5\left( {-4} \right)^2 + 6 &= 86 \\
     5\left( {16} \right) + 6 &= 86 \\
     80 + 6 &= 86 \\
     86 &= 86  \end{align}\)