Given equation is 4x−3(2x+3)+128=0..(i) Put 2x=y in Eq. (i), we get ⇒(2x)2−3(2x⋅23)+128=0 ⇒y2−3(8y)+128=0 ⇒y2−24y+128=0 ⇒y2−16y−8y+128=0 ⇒y(y−16)−8(y−16)=0 ⇒(y−16)(y−8)=0 ⇒y=16,8 ⇒2x=16 or 2x=8 ⇒2x=24 or 2x=23 ⇒x=4,3 ∴ Sum of the root =4+3=7