Mời các best môn toán thông não giúp em với ạ em hứa sẽ tim và cho 5 sao ạ
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`15)`
Với `x>0` ta có :
`A=(3x)/sqrtx+sqrt(9x)/3-sqrt(4x)`
`=3sqrtx+(3sqrtx)/3-2sqrtx`
`=sqrtx+sqrtx`
`=2sqrtx`
Vậy `A=2sqrtx` với `x>0`
`16)`
`P=sqrt16-root3 18+sqrt12/sqrt3`
`=sqrt(4^2)-root3 (2^3)+sqrt(2^2*3)/sqrt3`
`=4-2+(2sqrt3)/sqrt3`
`=2+2`
`=4`
Vậy `P=4`
`17)`
`A=2/(3+sqrt7)+sqrt28/2-2`
`=(2(3-sqrt7))/((3+sqrt7)(3-sqrt7))+sqrt(2^2*7)/2-2`
`=(2(3-sqrt7))/(9-7)+(2sqrt7)/2-2`
`=(2(3-sqrt7))/2+sqrt7-2`
`=3-sqrt7+sqrt7-2`
`=1`
Vậy `A=1`
`#td`