Definite integrals, rules

Summary

  • Integral of a constant. For any constant ,

\[\int_{a}^{b}{ ‍ }kdx=k\left( b-a \right)\]

  • Constant law. For any constant \(k\) ,

\[\int_{a}^{b}{ ‍ }kf\left( x \right)dx=k\int_{a}^{b}{ ‍ }f\left( x \right)dx\]

  • Addition law,

\[\int_{a}^{b}{ ‍ }\left( f\left( x \right)+g\left( x \right) \right)dx=\int_{a}^{b}{ ‍ }f\left( x \right)dx+\int_{a}^{b}{ ‍ }g\left( x \right)dx\]

  • Domain law. For any \(c∈[a,b]\) ,

\[\int_{a}^{b}{ ‍ }f\left( x \right)dx=\int_{a}^{c}{ ‍ }f\left( x \right)dx+\int_{c}^{b}{ ‍ }f\left( x \right)dx\]