Exponential and Logarithmic Equations: Background You’ll Need 3

  • Solve linear and quadratic equations

Solve Linear and Quadratic Equations

solving equations

Linear equations are solved with inverse operations. Quadratic equations are solved by factoring or applying the quadratic formula.

Solve [latex]3x - 7 = 11[/latex].

\begin{aligned}
3x – 7 &= 11 && \text{Start with the equation.} \\[6pt]
3x &= 18 && \text{Add 7 to both sides.} \\[6pt]
x &= 6 && \text{Divide both sides by 3.}
\end{aligned}

The solution is [latex]x = 6[/latex].

Solve [latex]4x - 5 = 2x + 7[/latex].

\begin{aligned}
4x – 5 &= 2x + 7 && \text{Start with the equation.} \\[6pt]
4x – 2x – 5 &= 7 && \text{Subtract $2x$ from both sides.} \\[6pt]
2x – 5 &= 7 && \text{Simplify.} \\[6pt]
2x &= 12 && \text{Add 5 to both sides.} \\[6pt]
x &= 6 && \text{Divide both sides by 2.}
\end{aligned}

The solution is [latex]x = 6[/latex].

A quadratic equation has a variable raised to the second power as the highest exponent (degree of 2).

Solve [latex]x^2 - 5x + 6 = 0[/latex].

\begin{aligned}
x^2 – 5x + 6 &= 0 && \text{Start with the quadratic} \\[6pt]
(x – 2)(x – 3) &= 0 && \text{Factor the trinomial} \\[6pt]
x – 2 &= 0 \quad \text{or} \quad x – 3 = 0 \\[6pt]
x &= 2 \quad \text{or} \quad x = 3
\end{aligned}

The solutions are [latex]x = 2[/latex] and [latex]x = 3[/latex].