While solving some problems on general organic chemistry, I came across this question that asked for the nature of inductive effects of $\ce{-CH_3}, \ce{-CO_2^-}, \ce{-Br}, \ce{-NH_3^+}$.
And in the solution to that problem, it says $\ce{-CO_2^-}$ shows $\ce{+I}$ effect.
How is it possible that the carboxylate ion with its two electronegative oxygen atoms shows a positive inductive effect instead of attracting a negative charge towards itself?
Please provide clarification on this.
