1. a) 20+11=31
b)12- 18=-6
c) -4 radical 18 +20 radical 2 = -12 radical 2+ 20 radical 2 = 8 radical 2
d)20 - 160 = -140
2. radical 3 + 2 - radical 3 = 2
radical 3 -2 plus radical 3 = 2 radical 3 - 2
5.a) mai mare 6 radical 5
b) 2 radical 2 +2 radical 6 supra 2 = 2(radical 2 +radical 6) supra 2 =radical 2 + radical 6)
c)x = radical 15