Đáp án:
`C=2sqrt5`
`D=25`
Giải thích các bước giải:
`c)C=(sqrt5+sqrt3)(5-sqrt{15})`
`C=(sqrt5+sqrt3)(5-sqrt{5.3})`
`C=sqrt5(sqrt5+sqrt3)(sqrt5-sqrt3)`
`C=sqrt5(5-3)`
`C=2sqrt5`
`D=(sqrt{32}-sqrt{50}+sqrt{27})(sqrt{27}+sqrt{50}-sqrt{32})`
`D=[sqrt{27}-(sqrt{50}-sqrt{32}][sqrt{27}+(sqrt{50}-sqrt{32})]`
`D=sqrt{27}^2-(sqrt50-sqrt32)^2`
`D=27-(50+32-2sqrt{50.32})`
`D=27-(82-2sqrt{25.2.2.16})`
`D=27-(82-2sqrt{(5.2.4)^2})`
`D=27-(82-2|5.2.4|)`
`D=27-82+2.40`
`D=27-82+80=25`