Question

Va rog repede daca puteti dar doar punctul h)

Answer 1

h) 20+25+30+...+100=5(4+5+6+...20)=5·(1+2+3+4+5+6+...+20-1-2-3)=5· (20·21/2 -6)=5·(210-6)=5·204=1020

Answer 2

h. 5(4+5+...20)=
5[ (1+2+3+4+5.....+20) - 1-2-3 ]=
5·( 20·21/2 -6)=
5·(210-6)=
5·204 =
1020