常数和基本初等函数导数公式推导

常数和基本初等函数导数公式:

1. c=0

2. (xn)=nxn1
(1). (x)=12x
(2). (1x)=1x2

3. (sinx)=cosx

4. (cosx)=sinx

5. (lnx)=1x

6. (logax)=logaex

7. (ax)=axlna
(1). (ex)=ex

8. (tanx)=sec2x

9. (cotx)=csc2x

10. (secx)=secxtanx

11. (cscx)=cscxcotx

12. (arcsinx)=11x2

13. (arccosx)=11x2

14. (arctanx)=11+x2

15. (arccotx)=11+x2


下面对导数公式进行推导:

(xn)=nxn1

由导数的定义:

limΔx0f(x+Δx)f(x)Δx

得:
(xn)=limΔx0(x+Δx)00nxnΔx

=limΔx0nm=1CmnxmΔxnmxnΔx

=limΔx0C0nx0Δxn+C1nx1Δxn1++Cn1nxn1Δx1+CnnxnΔx0xnΔx

=limΔx0C0nx0Δxn+C1nx1Δxn1++Cn1nxn1Δx1Δx

=nxn1


(sinx)=cosx

由导数的定义:

limΔx0f(x+Δx)f(x)Δx

得:
(sinx)=limΔx0sin(x+Δx)sinxΔx

=limΔx02cosx+Δx+x2sinx+Δxx2Δx

=limΔx02cos(x+Δx2)sinΔx22Δx2

=limΔx0cos(x+Δx2)

=cosx


(cosx)=sinx

由导数的定义:

limΔx0f(x+Δx)f(x)Δx

得:
(cosx)=limΔx0cos(x+Δx)cosxΔx

=limΔx02sinx+Δx+x2sinx+Δxx2Δx

=limΔx02sin(x+Δx2)sinΔx22Δx2

=limΔx0sin(x+Δx2)

=sinx


(lnx)=1x

由导数的定义:

limΔx0f(x+Δx)f(x)Δx

得:
(lnx)=limΔx0ln(x+Δx)lnxΔx

=limΔx0ln(x+Δxx)Δx

=limΔx0ln(1+Δxx)Δxxx

=1x


(logax)=logaex

由导数的定义:

limΔx0f(x+Δx)f(x)Δx

得:
(logax)=limΔx0loga(x+Δx)logaxΔx

=limΔx0loga(1+Δxx)Δx

=limΔx0loga(1+1xΔx)xΔxΔxxΔx

=limΔx0logaeΔxxΔx

=limΔx0ΔxxlogaeΔx

=logaex


(ax)=axlna

由导数的定义:

limΔx0f(x+Δx)f(x)Δx

得:
(ax)=limΔx0ax+ΔxaxΔx

=limΔx0ax(aΔx1)Δx

=axlimΔx0ΔxlnaΔx

=axlna


(tanx)=sec2x

(tanx)=(sinxcosx)

=(sinx)cosxsinx(cosx)cos2x

=cos2x+sin2xcos2x

=sec2x


(cotx)=csc2x

(cotx)=(1tanx)

=(cosxsinx)

=(cosx)sinxcosx(sinx)sin2x

=csc2x


(secx)=secxtanx

(secx)=(1cosx)

=1cosx1(cosx)cos2x

=sinxcos2x

=secxtanx


(cscx)=cscxcotx

(cscx)=(1sinx)

=1sinx1(sinx)sin2x

=cosxsin2x

=cscxcotx


(arcsinx)=11x2

y=arcsinxx=siny

(arcsinx)=(1siny)

=1cosy

=11sin2y

=11x2


(arccosx)=11x2

y=arccosxx=cosy

(arccosx)=(1cosy)

=1siny

=11cos2y

=11x2


(arctanx)=11+x2

y=arctanxx=tany

(arctanx)=(1tany)

=1sec2y

=11+tan2y

=11+x2


(arccotx)=11+x2

y=arccotxx=coty

(arccotx)=(1coty)

=1csc2y

=11+cot2y

=11+x2

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