Hướng dẫn trả lời:
c) `{2sqrt24 - sqrt120}/{4sqrt5 - 8} + {3sqrt2 + sqrt30}/{sqrt20 + sqrt12}`
`= {4sqrt6 - 2sqrt30}/{4sqrt5 - 8} + {3sqrt2 + sqrt30}/{2sqrt5 + 2sqrt3}`
`= {2sqrt6cdot(2 - sqrt5)}/{4cdot(sqrt5 - 2)} + {sqrt6cdot(sqrt3 + sqrt5)}/{2cdot(sqrt5 + sqrt3)}`
`= {2sqrt6cdot(2 - sqrt5)}/{-4cdot(2 - sqrt5)} + {sqrt6cdot(sqrt3 + sqrt5)}/{2cdot(sqrt5 + sqrt3)}`
`= {-2sqrt6}/{4} + {sqrt6}/{2}`
`= {-sqrt6}/{2} + {sqrt6}/{2}`
`= 0`
Đáp án:
`= 0`
