Question

Ma ajuta cineva ?va rog...

Answer 1

a) (2+4+6+...+80)/(1+2+3+...40)=2*(1+2+3+...+40)/(1+2+3+...+40)=2
b) (10+20+...90)/(5+10+...+45)=(10*(1+2+3+...+9))/(5(1+2+...+9))=
=10/5=2

Answer 2

a. factor comun in prima paranteza 2
2(1+2+....+40):(1+2+....+40)=2
b. la fel
2(5+10+15+....+45):(5+10+15+...+45)=2