Question

Вывести формулу (√х)^'=1/(2√x)

Answer 1

Объяснение:

$\sqrt{x} =x^{\frac{1}{2} }\\\sqrt{x}'=x^{\frac{1}{2} }=\frac{1}{2} *x^{\frac{1}{2}-1}=\frac{1}{2} *x^{-\frac{1}{2}}=\frac{1}{2x^{\frac{1}{2}}} =\frac{1}{2\sqrt{x}}$

Answer 2

$(\sqrt{x})' = \displaystyle \lim_{\Delta x \to 0} \dfrac{\Delta f}{\Delta x} = \lim_{\Delta x \to 0} \dfrac{f(x + \Delta x) - f(x)}{\Delta x} = \lim_{\Delta x \to 0} \dfrac{\sqrt{x + \Delta x} - \sqrt{x}}{\Delta x} =$

$= \left\{\dfrac{0}{0} \right\} = \displaystyle \lim_{\Delta x \to 0} \dfrac{(\sqrt{x + \Delta x} - \sqrt{x})(\sqrt{x + \Delta x} + \sqrt{x})}{\Delta x(\sqrt{x + \Delta x} + \sqrt{x})} =$

$= \displaystyle \lim_{\Delta x \to 0} \dfrac{(\sqrt{x + \Delta x})^{2} - (\sqrt{x})^{2}}{\Delta x (\sqrt{x + \Delta x} + \sqrt{x})} = \lim_{\Delta x \to 0} \dfrac{x + \Delta x - x}{\Delta x (\sqrt{x + \Delta x} + \sqrt{x})} =$

$= \displaystyle \lim_{\Delta x \to 0} \dfrac{\Delta x}{\Delta x (\sqrt{x + \Delta x} + \sqrt{x})} = \lim_{\Delta x \to 0} \dfrac{1}{\sqrt{x + \Delta x} + \sqrt{x}} = \dfrac{1}{\sqrt{x + 0} + \sqrt{x}} = \dfrac{1}{2\sqrt{x}}$