$ I_{min} \propto (\sqrt I_1 - \sqrt I_2)^2$ 

$\text {here } I_1 = I , I_2 = \frac{I}{2} ,\text{because Intensity from one slit is half as compared to other}$

$\Rightarrow I_{min} \propto (I - \frac{I}{2})^2 $ 

$ I_{min} \propto (\sqrt I_1 - \sqrt I_2)^2$ 

$\text {here } I_1 = I , I_2 = \frac{I}{2} ,\text{because Intensity from one slit is half as compared to other}$

$\Rightarrow I_{min} \propto (I + \frac{I}{2})^2 $ 

$\text{Intensity of maxima decreases and minima increases}$