first we times the whole fraction by √24 √24*√24=24 so the bottom of the fraction is 24
√12*√24=288
√288
the biggest square number that goes into 288 is 144 12² so it becomes √144*2
then it becomes 12√2 and the bottom is 24 so it's
12√2/24 and we can simplify this to √2/2
