Tìm đạo hàm bằng định nghĩa tại x0 1.y=c (c là hằng số) 2.y=căn x 3.y=1/x 4. y-x^2 15/11/2021 Bởi Eva Tìm đạo hàm bằng định nghĩa tại x0 1.y=c (c là hằng số) 2.y=căn x 3.y=1/x 4. y-x^2
1) $y’=$ $\lim_{n \to x_{o}} \dfrac{c-c}{x-x_{o}}$ = $\lim_{n \to x_{o}} \dfrac{0}{x-x_{o}}$ = $\lim_{n \to x_{o}} 0$ = $0$ . 2) $y’ = \lim_{n \to x_{o}} \dfrac{\sqrt[]{x}-\sqrt[]{x_{o}}}{x-x_{o}}$ = $\lim_{n \to x_{o}} \dfrac{\sqrt[]{x}-\sqrt[]{x_{o}}}{(\sqrt[]{x}-\sqrt[]{x_{o}}).(\sqrt[]{x}+\sqrt[]{x_{o}})}$ = $\lim_{n \to x_{o}} \dfrac{1}{\sqrt[]{x}+\sqrt[]{x_{o}}}$ = $ \dfrac{1}{\sqrt[]{x_{o}}+\sqrt[]{x_{o}}}$ = $ \dfrac{1}{2\sqrt[]{x_{o}}}$ . 3) $y’=\lim_{n \to x_{o}}\dfrac{\dfrac{1}{x}-\dfrac{1}{x_{o}}}{x-x_{o}}$ $=\lim_{n \to x_{o}}\dfrac{\dfrac{x_{o}-x}{x.x_{o}}}{x-x_{o}}$ $=\lim_{n \to x_{o}}\dfrac{x_{o}-x}{x.x_{o}.(x-x_{o})}$ $=\lim_{n \to x_{o}}\dfrac{x_{o}-x}{x.x_{o}.(x-x_{o})}$ $=\lim_{n \to x_{o}}\dfrac{1}{x.x_{o}}$ $=\dfrac{1}{x_{o}.x_{o}}$ $=\dfrac{1}{x_{o}^2}$ . 4) $y’=$$\lim_{n \to x_{o}}\dfrac{x^2-x_{o}^2}{x-x_{o}}$ $=\lim_{n \to x_{o}}\dfrac{(x-x_{o})(x+x_{o})}{x-x_{o}}$ $=\lim_{n \to x_{o}}x+x_{o}$ $=x_{o}+x_{o}$ $=2x_{o}$ Bình luận
1) $y’=$ $\lim_{n \to x_{o}} \dfrac{c-c}{x-x_{o}}$
= $\lim_{n \to x_{o}} \dfrac{0}{x-x_{o}}$
= $\lim_{n \to x_{o}} 0$ = $0$
.
2) $y’ = \lim_{n \to x_{o}} \dfrac{\sqrt[]{x}-\sqrt[]{x_{o}}}{x-x_{o}}$
= $\lim_{n \to x_{o}} \dfrac{\sqrt[]{x}-\sqrt[]{x_{o}}}{(\sqrt[]{x}-\sqrt[]{x_{o}}).(\sqrt[]{x}+\sqrt[]{x_{o}})}$
= $\lim_{n \to x_{o}} \dfrac{1}{\sqrt[]{x}+\sqrt[]{x_{o}}}$
= $ \dfrac{1}{\sqrt[]{x_{o}}+\sqrt[]{x_{o}}}$
= $ \dfrac{1}{2\sqrt[]{x_{o}}}$
.
3) $y’=\lim_{n \to x_{o}}\dfrac{\dfrac{1}{x}-\dfrac{1}{x_{o}}}{x-x_{o}}$
$=\lim_{n \to x_{o}}\dfrac{\dfrac{x_{o}-x}{x.x_{o}}}{x-x_{o}}$
$=\lim_{n \to x_{o}}\dfrac{x_{o}-x}{x.x_{o}.(x-x_{o})}$
$=\lim_{n \to x_{o}}\dfrac{x_{o}-x}{x.x_{o}.(x-x_{o})}$
$=\lim_{n \to x_{o}}\dfrac{1}{x.x_{o}}$
$=\dfrac{1}{x_{o}.x_{o}}$
$=\dfrac{1}{x_{o}^2}$
.
4) $y’=$$\lim_{n \to x_{o}}\dfrac{x^2-x_{o}^2}{x-x_{o}}$
$=\lim_{n \to x_{o}}\dfrac{(x-x_{o})(x+x_{o})}{x-x_{o}}$
$=\lim_{n \to x_{o}}x+x_{o}$
$=x_{o}+x_{o}$
$=2x_{o}$