1. notice that you have two identical â6.. and so when you square them (multiply two of the same things) you get 6! so the answer for 1 is just 4*6 = 24
2. multiply the whole numbers, to get 15, then multiply the numbers under the â to get â240: 15â240
then you can factor out the â240 into â2*2*2*2*3*5
pair off what you can, and move it outside (so â2*2 = 2, and â2*2 = 2) 2*2*15*â3*5
60â15 is as simple as it gets!
3. the idea here is just to get the â3 out from the bottom:
4. again, gotta get the â3 off the bottom, so multiply top & bottom by 1 + â3 (notice you flipped the - to a +... this makes the â3 go away! this is a little trick you just kinda have to know...)
Use the fact that sqrt(x)*sqrt(y)=sqrt(xy). (This fact follows from the fact that both sqrt(x)*sqrt(y) and sqrt(xy) both have the same square: xy, and both are positive, so they're equal.)
That fact, together with factoring the "radicands" (numbers inside the square root signs) into primes should do it for you.