Răspuns :
a=1+2+3+...+100+51×101
a = 101×100:2 + 51×101
a = 101×50+51×101
a = 101×(50+51)
a = 101×101
a = 101^2 (este patrat perfect)
a = 101×100:2 + 51×101
a = 101×50+51×101
a = 101×(50+51)
a = 101×101
a = 101^2 (este patrat perfect)
a=1+2+3+...+100+51×101
1+2+3+...+100=(1+100)×100:2=101×50
a=101×50+51×101
a=101×(50+51)
a=101×101
a=101^2
a este pătrat perfect
1+2+3+...+100=(1+100)×100:2=101×50
a=101×50+51×101
a=101×(50+51)
a=101×101
a=101^2
a este pătrat perfect