Răspuns:
A)1+2+3+...+200=
=200 x(1+200):2
=200 x 201:2
=200 x 100,5
=20100
B)2+4+6+...+200=
=200 x(2+200):2
=200 x 202:2
=200 x 101
=20200
C)5+10+15+...+200=
=200 x (5+200):2
=200 x 205:2
=200 x 102,5
=20500
D)15+16+...+200=
=200 x (15+200):2
=200 x 215:2
=200 x 107,5
=21500
E) 1+3+5+...+199=
=199 x (1+199):2
=199 x 200:2
=199 x 100
=19900
F)1+3+5+...+151=
=151 x (1+151):2
=151 x 152:2
=151 x 76
=11476
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