Subjects algebra

Function Division E3A1Dd

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1. **State the problem:** We are given two functions: $$f(x) = 3x - 30$$ $$g(x) = x^2 - x - 90$$ We need to find the function \(\frac{f}{g}(x)\) and determine its domain. 2. **Formula used:** The division of two functions is defined as: $$\left(\frac{f}{g}\right)(x) = \frac{f(x)}{g(x)}$$ The domain of \(\frac{f}{g}(x)\) includes all values of \(x\) where \(g(x) \neq 0\). 3. **Find \(\frac{f}{g}(x)\):** $$\frac{f}{g}(x) = \frac{3x - 30}{x^2 - x - 90}$$ 4. **Factor numerator and denominator:** Numerator: $$3x - 30 = 3(x - 10)$$ Denominator: Factor \(x^2 - x - 90\): find two numbers that multiply to \(-90\) and add to \(-1\). These are \(-10\) and \(9\), so: $$x^2 - x - 90 = (x - 10)(x + 9)$$ 5. **Simplify the fraction:** $$\frac{3(x - 10)}{(x - 10)(x + 9)}$$ Cancel the common factor \(x - 10\) (noting \(x \neq 10\) to avoid division by zero): $$\frac{3\cancel{(x - 10)}}{\cancel{(x - 10)}(x + 9)} = \frac{3}{x + 9}$$ 6. **Domain:** The original denominator \(g(x) = (x - 10)(x + 9)\) cannot be zero, so: $$x - 10 \neq 0 \Rightarrow x \neq 10$$ $$x + 9 \neq 0 \Rightarrow x \neq -9$$ Therefore, the domain of \(\frac{f}{g}(x)\) is all real numbers except \(x = 10\) and \(x = -9\). **Final answers:** $$\left(\frac{f}{g}\right)(x) = \frac{3}{x + 9}$$ Domain: \(x \neq 10, -9\)