Hướng dẫn giải:
`h,` `sqrt(3/15):sqrt(36/45)`
`=sqrt(3/15:36/45)`
`=sqrt(1/4)=1/2`
`i,` `(sqrt25+sqrt245-sqrt5):sqrt5`
`=sqrt(25:5)+sqrt(245:5)-sqrt(5:5)`
`=sqrt5+sqrt49-1`
`=sqrt5+7-1`
`=6+sqrt5`
`k,` `(sqrt(1/7)-sqrt(16/7)+sqrt7):sqrt7`
`=sqrt(1/7:7)-sqrt(16/7:7)+sqrt(7:7)`
`=sqrt(1/49)-sqrt(16/49)+sqrt1`
`=1/7-4/7+1`
`=4/7`
`m,sqrt((5(38^2-17^2))/(8(47^2-19^2)))`
`=sqrt((5(38-17)(38+17))/(8(47-19)(47+19))`
`=sqrt((5.21.55)/(8.28.66))`
`=sqrt((5.3.7.5.11)/(8.7.4.2.3.11))`
`=sqrt(25/64)`
`=5/8`