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calculează apoi simplifica
a) 1/5+2/5+3/5+4/5+...+9/5
b)1/7+2/7+3/7+...+20/7


va rog dau coroană ​


Răspuns :

Răspuns:

a) 1+2+3+4+5+6+7+8+9/5

=45/5=9/1= 9

b)1+2+3+...+20/7

=210/7=30/1=30

Răspuns:

a) 1/5+2/5+3/5+4/5+...+9/5

=(1+2+3+...+9)/5

=9×(9+1)/5

=9×10/5

=9×2

=18

b)1/7+2/7+3/7+...+20/7

=(1+2+3+...+20)/7

=20×(20+1)/7

=20×21/7

=20×3

=60

Am folosit formula pt suma lui Gauss

1+2+3+4+ ....+n = n ×(n+1) /2