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Find the domain of $\frac{x^2 + 10x + 21}{x^2 + 4x - 21}$. (Express your answer using interval notation.)

Guest Aug 30, 2017
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Find the domain of $\frac{x^2 + 10x + 21}{x^2 + 4x - 21}$. (Express your answer using interval notation.)

$$\frac{x^2 + 10x + 21}{x^2 + 4x - 21}\\ =\frac{(x+3)(x+7)}{(x-3)(x+7)}\\ x\ne-7 \qquad x\ne3\\ Domain\quad(-\infty,-7)\cup (-7,3) \cup(3,\infty)$$

I think this is interval notation..?...

Melody  Aug 30, 2017