Question

a) 1+2+3+...+10=
b) 11+12+...+20=
c) 21+22+...+29+30=
d) 91+92+...+100=
Este cu SUMA LUI GAUSS ajutor!!!!

Answer 1

1+2+3+.....+10=10(10-1)/2=10*9/2=5*9=45

Answer 2

a) 1+2+3+4+5+6+7+8+9+10= (1+10)+(2+9)+(3+8) + (4+7)+(5+6) = 11+11+11+11+11= 11 X 5 = 55 

b) 11+12+13+14+15+16+17+18+19+20=(11+20)+(12+19)+(13+18)+(14+17)+(15+16)= 31+31+31+31+31=31X5= 155

c) 21+22+23+24+25+26+27+28+29+30= (21+30)+(22+29)+(23+28)+(24+27)+(25+26)= 51+51+51+51+51= 51X5= 255

d) 91+92+93+94+95+96+97+98+99+100= (91+100)+(92+99)+(93+98) + (94+97) + (95+96)= 191+191+191+191+191=191X5= 955