а)√121-10√6.4*√0.1
б)2√5-√45+√80

√121 -10√6.4*√0.1=11-10√(6.4*0.1)= 11-10*0.8=11-8=32√5 - √45 +√80 =2√5-√(9*5) + √(16*5) = 2√5 - 3√5 + 4√5 =3√5