Răspuns :
√2+√8+√18....+√200=
=√2+2√2+3√2....+10√2=
=√2(1+2+3....+10)=
=√2 × 10×(10+1)/2=
=√2 × 5×11=
=55√2
=√2+2√2+3√2....+10√2=
=√2(1+2+3....+10)=
=√2 × 10×(10+1)/2=
=√2 × 5×11=
=55√2