This is a wire thats going from minus infinity to zero i$\text{'}$m using cylindrical coordinates I need to find the H for a point but I$\text{'}$m not able to calculate the last written expression that involves limits the variable is z$\text{'}$

Z and Ro are not dependent on z$\text{'}$ i$\text{'}$d be very thankful if you could solve the limit thank you

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vec$(H)=\frac{-Ivec({)}_{}}{4}\underset{-}{lim}(\frac{z}{{}^2\sqrt[\phantom{2}]{{}^2+(z{)}^2}}-\frac{z-L}{{}^2\sqrt[\phantom{2}]{{}^2+(z-L{)}^2}})$

$$ doing $u-$sub $z-z^{\text{'}}=u-d{z}^{\text{'}}$

$$

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