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(11+22+55+...+99):(1+2+3+...9)


Răspuns :

nr term=(99-11):11+1
=88:11+1=9
S=(99+1)x9:2
S=100x9:2
S=50x9
S=450

nr term2 = (9-1):1+1 = 9
S2=(9+1)x9:2
S2=10x9:2
S2=45

S:S2= 450:45=10