√8+10√2 = √(2*4)+10√2 = 2√2+10√2 = 12√2
√20-5√5 = √(4*5)-5√5 = 2√5-5√5 = -3√5
√28+√63 = √(4*7)+√(7*9) = 2√7+3√7 = 5√7
2√50-5√200 = 2√(2*25)-5√(2*100) = 10√2-50√2 = -40√2
√99-√176 = √(9*11)-√(11*16) = 3√11-4√11 = -√11
5√92-√2300 = 5√(4*23)-√(23*100) = 10√23-10√23 = 0