`a)` `7+4\sqrt{3}`
`=` `4` `+` `4`$\sqrt{3}$ `+``3`
`=` $2^{2}$ `+``2.2`$\sqrt{3}$
`=` $(2+\sqrt{3})^{2}$
`b)` `11``-``6`$\sqrt{2}$
`=` `9``-``2.3`$\sqrt{2}$`+` `2`
`=` $3^{2}$ `-``2.3`$\sqrt{2}$`+` ($\sqrt{2}) ^{2}$
`=` $(3-\sqrt{2} )^{2}$
Chúc bạn học tốt!!
@Katniss