Solution 2 :

(i) VDS = 0 ; VGS = 2V

VGS > VT -----------------------------------------> Transistor : ON

VDS < VGS - VT ---------------------------------> Linear Mode

VDS = 0 --------------------------------------------> IDS = 0 A

(ii) VDS = 0.5V ; VGS = 2.5V

VGS > VT -----------------------------------------> Transistor : ON

VDS < VGS - VT ---------------------------------> Linear Mode

IDS = K [ ( VGS - VT ) VDS - (VDS^2/2) ]

= 25 [ ( 2.5 - 1 ) 0.5 - ( 0.5^2/2 )]

= 15.625 uA

(iii) VDS = 1.2V ; VGS = 0.8V

VGS < VT------------------------------------------> Transistor : Cut - off

IDS =0 A

(iv) VDS = 1.3V ; VGS = 2V

VGS > VT -----------------------------------------> Transistor : ON

VDS > VGS - VT ---------------------------------> Saturation Mode

IDS = (K/2) ( VGS - VT )^2

= (25/2) ( 2 - 1 )^2

= 12.5 uA