(I ) 4x^(2)+20x+25=(2x)^(2)+2xx2xxx5+(5)^(2) =(2x+5)^(2) [using identity ,a^(2)+2ab+b^(2)=(a+b)^(2)] (ii) 9y^(2)-66yz+121z^(2)=(3y)^(2)-2xx3yxx11z+(11z)^(2) =(3y-11z)^(2) [using identity ,a^(2)-2ab+B^(2)=(a-b)^(2)] (iii) (2x...