Question

Ex 8 a și b rapid va rog

Answer 1

Răspuns:

Explicație pas cu pas:

Aplicam suma Gauss

a) (1+2+3+...+50)+(1+2+3+....+200)=50·51/2+200·201/2=

=25·51+100·201=25(51+4·201)=25(51+804)=25·855=21 375

b)31+32+...+100=(1+2+3+...+100)-(1+2+3+...+30)=100·101/2-30·31/2=

=50·101-15·31=5050-465=4 585

Answer 2

Vom aplica suma lui gaus care zice: a+(a+1)+(a+2)+……+(a+n)= (a+n) x [a+(n+1)] :2

8. a) (1+2+3+…..+50)+(1+2+……+200)= 50x51:2 +200x201:2=1275+20100=21375

b)31+32+….+100= 100x101:2 - 30x31:2=5050-465=4585