Example

Example of Determining the Domain of the Rational Function R(x)=2x214x4x216x48R(x) = \frac{2x^2 - 14x}{4x^2 - 16x - 48}

To find the domain of the rational function R(x)=2x214x4x216x48R(x) = \frac{2x^2 - 14x}{4x^2 - 16x - 48}, we must exclude any values that would cause division by zero. Following the standard procedure, we first set the denominator equal to zero:

4x216x48=04x^2 - 16x - 48 = 0

Next, solve the equation. Begin by factoring out the greatest common factor:

4(x24x12)=04(x^2 - 4x - 12) = 0

Then, factor the trinomial completely:

4(x6)(x+2)=04(x - 6)(x + 2) = 0

Applying the Zero Product Property, set each variable factor to zero:

x6=0orx+2=0x - 6 = 0 \quad \text{or} \quad x + 2 = 0

Solving these gives the excluded values:

x=6orx=2x = 6 \quad \text{or} \quad x = -2

Finally, the domain is all real numbers excluding these restricted values. Therefore, the domain of R(x)R(x) is all real numbers where x6x \neq 6 and x2x \neq -2.

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Updated 2026-05-25

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