a) 5√18+3√2-√98=
=5×3√2+3√2-7√2=
=15√2+3√2-7√2=
=18√2-7√2=11√2
b) 7√5+2√125-√20=
=7√5+2×5√5-2√5=
=7√5+10√5-2√5=
=17√5-2√5=15√5
c) 4√7-3√28+√7=
=4√7-3×2√7+√7=
=4√7-6√7+√7=
= -2√7+√7= -√7
