# A property of complex integration

It is simple one. In my school book it says

is there any mistake here? Because i think otherwise.

btw question is showing $\int_{γ}(c_1f+c_2g)=c_1\int_{γ}f+c_2\int_{γ}g$

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Yes, clearly these are mistakes. –  Robert Israel Dec 23 '12 at 23:35

$$(u+i v) (x' + i y') = (u x' - v y') + i (v x' + u y')$$
The term $(u x'+v y')$ makes no sense, and is the result of a clear error.