Subjects calculus

Exponential Limit 7C893D

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Question: top-left: none center: lim x→∞ ( (4^x + 9^x) ────────── x )^1/x top-right: none bottom-left: none bottom-right: none it is over x
1. **Problem statement:** Evaluate $$\lim_{x\to\infty}\left(\frac{4^x+9^x}{x}\right)^{1/x}.$$ 2. **Use the dominant term rule.** For large $$x,$$ the bigger exponential dominates, so $$4^x+9^x\sim 9^x.$$ Thus, $$\frac{4^x+9^x}{x}\sim \frac{9^x}{x}.$$ 3. **Rewrite the expression.** $$\left(\frac{4^x+9^x}{x}\right)^{1/x}\sim \left(\frac{9^x}{x}\right)^{1/x}.$$ Now split the power: $$\left(\frac{9^x}{x}\right)^{1/x}=\frac{(9^x)^{1/x}}{x^{1/x}}.$$ 4. **Simplify each part.** $$\frac{(9^x)^{1/x}}{x^{1/x}}=\frac{9}{x^{1/x}}.$$ Also, $$\lim_{x\to\infty}x^{1/x}=1.$$ So the whole expression approaches $$\frac{9}{1}=9.$$ 5. **Final answer:** $$\boxed{9}$$