Question 192
note that 18=9*2, 50 = 25*2, 72 = 36*2. 9, 25 and 36 are squares of 3, 5 and 6 can be taken out of squar root as 3, 5, and 6 respectively. So, you get {{{3*sqrt(18)-sqrt(50)+2*sqrt(72) = 3*3*sqrt(2) - 5*sqrt(2) + 2*6*sqrt(72) = sqrt(2)*(3*3-5+2*6) = 16*sqrt(2)}}}