Đáp án+Giải thích các bước giải:
`50)(sqrt45+sqrt63)(sqrt7-sqrt5)`
`=sqrt9(sqrt7+sqrt5)(sqrt7-sqrt5)`
`=3.(7-5)`
`=3.2=6`
`52)(sqrt32-sqrt50+sqrt27)(sqrt27+sqrt50-sqrt32)`
`=[sqrt27-(sqrt50-sqrt32)][sqrt27+(sqrt50-sqrt32)]`
`=sqrt27^2-(sqrt50-sqrt32)^2`
`=27-(50+32-2sqrt{50.32})`
`=27-(82-2sqrt{25.2.2.16})`
`=27-82+2sqrt{(5.2.4)^2}`
`=-55+2.40`
`=-55+80`
`=25`
`54)(2sqrt112-5sqrt7+2sqrt63-2sqrt28).sqrt7`
`=(2sqrt{7.16}-5sqrt7+2sqrt{9.7}-2sqrt{4.7}).sqrt7`
`=(8sqrt7-5sqrt7+18sqrt7-4sqrt7).sqrt7`
`=17sqrt7.sqrt7`
`=17.7=119`