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A= 1-2+3-4 +...+99 -100
B = -2 -4 -6 -... - 98-100


Răspuns :

A= 1-2+3-4 +...+99 -100
A = -1 + (-1) + (-1) + ...+ (-1)
100:2 = 50
A = (-1) × 50
A = - 50

B = -2 -4 -6 -... - 98-100
B = -2×(1+2+3+...+49+50)
B = -2×(51×50:2)
B = -2 × 2 550:2
B = -2×1 275
B = - 2 550

A + B = (-50) + (-2 550) = - 2 600