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6+11+16+21+.........+506=

Răspuns :

6+11+16+21+.........+506=25856
nr termeni=(506-6):5+1
=500:5+1
=100+1
=101

S=(506+6)×101:2
= 512×101:2
=51.712:2
=25.856
Sper ca te-am ajutat!!!