integration

Put tan^-1x = y

x = tany

1 = sec²y dy/dx

1 = (1 + tan²y)dy/dx

1 = (1 + x²)dy/dx

dx/(1+x²) = dy/dx

(e^{arctan x})dx/(1+x²) = e^ydy =  e^{arctan x} + c

arctan x = tan^-1x

Regards,

Team,

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