a) x=3√8-√75+2√80=3•2√2-5√3+2•4√5=
=6√2-5√3+8√5
y=√32+5√27+3√20=4√2+5•3√3+3•2√5=
=4√2+15√3+6√5
media aritmetică=x+y/2
=6√2-5√3+8√5+4√2+15√3+6√5/2=
=10√2+10√3+14√5/2=2(5√2+5√3+7√5)/2=
=5√2+5√3+7√5=5(√2+√3)+7√5
b) x=2√8+2√80-√63=2•2√2+2•4√5-3√7=
=4√2+8√5-3√7
y=√72-2√20+3√63=6√2-2•2√5+3•3√7=
=6√2-4√5+9√7
media aritmetică=x+y/2=4√2+8√5-3√7+6√2-4√5+9√7/2=
=10√2+4√5+6√7/2=2(5√2+2√5+3√7)/2=
=5√2+2√5+3√7
