Find the domain of the function. \[ f(x)=\frac{8}{x^{2}-7 x-98} \] What is the domain of \( f \) ?
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To find the domain of the function \( f(x) = \frac{8}{x^{2} - 7x - 98} \), we need to determine where the function is defined. This function will be undefined wherever the denominator is zero, so we need to solve: \[ x^{2} - 7x - 98 = 0 \] Using the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), where \( a=1 \), \( b=-7 \), and \( c=-98 \): 1. Calculate the discriminant: \( b^2 - 4ac = (-7)^2 - 4 \cdot 1 \cdot (-98) = 49 + 392 = 441 \) 2. Plug into the quadratic formula: \( x = \frac{7 \pm 21}{2} \) This results in the solutions: \( x = 14 \) and \( x = -7 \). Thus, the function is undefined at \( x = 14 \) and \( x = -7 \). Therefore, the domain of \( f \) is all real numbers except these two points: \[ \text{Domain: } (-\infty, -7) \cup (-7, 14) \cup (14, \infty) \]