Question

Ajutoor... Vreau rezolvare pentru clasa IV

Answer 1

S = -0+1+2-3+4+5-6+7+8-...+97+98-99
S2 = -3-6-9-12-...-96
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S+S2 = -0+1+2-3-3+4+5-6-6+7+8-9-9+10+11-12-12+13+14-15-15+...-96-96+97+98-99

S+S2 =(-0+1+2-3)+(-3+4+5-6)+(-6+7+8-9)+(-9+10+11-12)+(-12+13+14-15)+...+
+(-96+97+98-99)

S+S2 = 0+0+0+...+0
S+S2 = 0
S = -S2
S = -(-3-6-9-12-..-96)
S = 3+6+9+12+...+96
S = 3×(1+2+3+...+32)
S = 3×(32×(32+1)/2)
S = 3×32×33/2
S = 3×16×33
S = 1.584