Đáp án:
`(4+sqrt{15})(sqrt{10}-sqrt6)sqrt{4-sqrt{15}}`
`= (4sqrt{10}-4sqrt6+sqrt{150}-sqrt{90})sqrt{4-sqrt{15}}`
`= (4sqrt{10}-4sqrt6+sqrt{5^2}sqrt6-sqrt{3^2}sqrt{10})sqrt{4-sqrt{15}}`
`= (4sqrt{10}-4sqrt6+5sqrt6-3sqrt{10})sqrt{4-sqrt{15}}`
`= (sqrt{10}+sqrt6)sqrt{4-sqrt{15}}`
`= sqrt{10(4-sqrt{15})} + sqrt{6(4-sqrt{15})}`
`= sqrt{40-10sqrt{15}} + sqrt{24-6sqrt{15}}`
`= sqrt{5^2-2*5*sqrt{15}+(sqrt{15})^2} + sqrt{3^2+2*3sqrt{15}+(sqrt{15})^2}`
`= sqrt{(5-sqrt{15})^2} + sqrt{(3-sqrt{15})^2}`
`= |5-sqrt{15}| + |3-sqrt{15}|`
`= 5 - sqrt{15} + sqrt{15} - 3`
`= 2`
