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# Finding integral - do we always add the constant... watch

1. When we have a question with that symbol then (3x+1)coz(2x)dx...
do we find the integral and then add +C... or do we just find the integral?
2. (Original post by aliceinwonder123)
When we have a question with that symbol then (3x+1)coz(2x)dx...
do we find the integral and then add +C... or do we just find the integral?
You need +C if the integral has no limits. An integral without limits is called indefinite.
3. If you differentiate a function with a constant, the derivative no longer contains the constant. But by the fundamental theorem of calculus, if you integrate the derivative you get the original function. So yes you need to add a +C otherwise you won't be able to recover the constant.
4. Always add the +C unless you are doing definite integration (i.e. finding the area bounded between the curve and x axis between two x co-ordinates - you minus one from the other so the Cs would cancel out and hence you don't need to calulate it)

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Updated: February 27, 2018
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