Verified answer

[tex]\displaystyle\bf\\1)\\\\61^{2} =(60+1)^{2} =60^{2} +2\cdot 60\cdot 1+1^{2}=3600+120+1=3721\\\\2)\\\\199^{2} =(200-1)^{2} =200^{2} -2\cdot 200\cdot 1+1^{2} =40000-400+1=\\\\=39601[/tex]