4.)
`7/(sqrt(13)-11)=7/(sqrt(13)-11)*(sqrt13+11)/(sqrt13+11)=(7*(sqrt13+11))/((sqrt(13)-11)*(sqrt13+11))=(7sqrt(13)+77)/(13-121)=color(red)(-(7sqrt(13)+77)/108)`



5.)
`(5-2sqrt3)/(3sqrt3-10)=(5-2sqrt3)/(3sqrt3-10)*(3sqrt3+10)/(3sqrt3+10)=((5-2sqrt3)*(3sqrt3+10))/((3sqrt3-10)*(3sqrt3+10))=(15sqrt3+50-18-20sqrt3)/(9*3-100)=color(red)((32-5sqrt3)/73)`



6.)
`(3sqrt5-2sqrt7)/(6sqrt7+2sqrt5)=(3sqrt5-2sqrt7)/(6sqrt7+2sqrt5)*(6sqrt7-2sqrt5)/(6sqrt7-2sqrt5)=((3sqrt5-2sqrt7)*(6sqrt7-2sqrt5))/((6sqrt7+2sqrt5)*(6sqrt7-2sqrt5))=(18sqrt35-30-84+4sqrt35)/(36*7-4*5)=color(red)((11sqrt35-57)/116)`


A feladatokat fehér színnel oldottam meg. Amennyiben megoldásnak jelölöd a választ elérhetővé teszem rendesen is. Előre is köszönöm