Câu hỏi
\(\underset{x\to {{2}^{2018}}}{\mathop{\lim }}\,\dfrac{{{x}^{2}}-{{4}^{2018}}}{x-{{2}^{2018}}}\) bằng
- A \({{2}^{2019}}\)
- B \(+\infty \)
- C 2
- D \({{2}^{2018}}\)
Lời giải chi tiết:
\(\underset{x\to {{2}^{2018}}}{\mathop{\lim }}\,\dfrac{{{x}^{2}}-{{4}^{2018}}}{x-{{2}^{2018}}}=\underset{x\to {{2}^{2018}}}{\mathop{\lim }}\,\dfrac{\left( x-{{2}^{2018}} \right)\left( x+{{2}^{2018}} \right)}{x-{{2}^{2018}}}\) \(=\underset{x\to {{2}^{2018}}}{\mathop{\lim }}\,\left( x+{{2}^{2018}} \right)={{2}^{2018}}+{{2}^{2018}}={{2}^{2019}}\)
Chọn A
Câu hỏi trước
