1. $\int \frac{1}{x(1+x)} dx =$
A: \[\ln{(x)}-\ln{\left( x+1\right) }+C\]
B: \[\ln{(x)}+\ln{\left( x+1\right) }+C\]
C: \[x-\ln{\left( x+1\right) }+C\]
D: \[-\ln{(x)}+\ln{\left( x+1\right) }+C\]
A: \[\ln{(x)}-\ln{\left( x+1\right) }+C\]
B: \[\ln{(x)}+\ln{\left( x+1\right) }+C\]
C: \[x-\ln{\left( x+1\right) }+C\]
D: \[-\ln{(x)}+\ln{\left( x+1\right) }+C\]
举一反三
- \( \int {({1 \over x} - {2 \over {\sqrt {1 - {x^2}} }})dx} = \)( ) A: \( \ln \left| x \right| + 2\arcsin x + C \) B: \( \ln \left| x \right| - 2\arcsin x + C \) C: \(- \ln \left| x \right| - 2\arcsin x + C \) D: \(- \ln \left| x \right| +2\arcsin x + C \)
- 函数$y = \ln x$，则${\left( {\ln x} \right)^{\left( n \right)}} = {\left( { - 1} \right)^{n - 1}}{{\left( {n - 1} \right)!} \over {{x^n}}}$。（ ）
- \(\int { { {\sec }^{3}}xdx}\)=( ) A: \(\frac{1}{2}\sec x\cot x-\frac{1}{2}\ln \left| \sec x+\tan x \right|+C\) B: \(\frac{1}{2}\sec x\tan x+\frac{1}{2}\ln \left| \sec x+\tan x \right|+C\) C: \(-\frac{1}{2}\csc x\tan x+\frac{1}{2}\ln \left| \sec x-\cot x \right|+C\) D: \(-\frac{1}{2}\sec x\tan x-\frac{1}{2}\ln \left| \csc x+\tan x \right|+C\)
- 函数\(z = {\left( {xy} \right)^x}\)的全微分为 A: \(dz = \left( { { {\left( {xy} \right)}^x} + \ln xy} \right)dx + x{\left( {xy} \right)^x}dy\) B: \(dz = \left( { { {\left( {xy} \right)}^x} + \ln xy} \right)dx + { { x { { \left( {xy} \right)}^x}} \over y}dy\) C: \(dz = {\left( {xy} \right)^x}\ln xydx + { { x { { \left( {xy} \right)}^x}} \over y}dy\) D: \(dz = {\left( {xy} \right)^x}\left( {1 + \ln xy} \right)dx + { { x { { \left( {xy} \right)}^x}} \over y}dy\)
- \( \int {\sec xdx} \)=( )。 A: \( \ln \left| {\csc x + \tan x} \right| + C \) B: \( \ln \left| {\sec x + \cot x} \right| + C \) C: \( \ln \left| {\sec x + \tan x} \right| + C \) D: \( \ln \left| {\csc x + \cot x} \right| + C \)