IIT JEE , AIEEE Forum - Mathematics , Integral Calculus

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A double integral is always associated over an area in XY plane, as a single integral is associated with an interval.
The only kind of double integrals that you need to know how to solve are the ones in which the function is such that the x and y terms can be separated.
e.g
_{x = 0}

¹ _{y = 0}

² x² y dx dy =( ₀

¹x² dx )(₀

² y dy) which you can easily evaluate.
The area on which the integration is performed is a rectangle with vertices's (0,0),(1,0),(0,2) & (1,2)

Note that this isn' the entire theory of double integrals, but these are the types of double integrals that you might encounter at +2 level.

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