Tính nhanh:

$a) {34}^2+{66}^2+68.66;$

$b){74}^2+{24}^2-48.74;$

Giải:

$a) {34}^2+ {66}^2+68.66 = {34}^2+ 2.34 . 66 + {66}^2 = {(34 + 66)}^2 = {100}^2 = 10000.$

$b) {74}^2 + {24}^2 – 48.74 = {74}^2 - 2 .74. 24 + {24}^2 = {(74 - 24)}^2 ={50}^2 =2500$