Question

(2+4+6+...+20)-(1+3+5...+19)

Answer 1

2(10×10+1/2)-(1+2+3+...+20)-(2+4+6+...+20)=

2×55-210-2×55=

110-210-110=

-210

sper ca te-am ajutat :)

Answer 2

Răspuns:

2+4+6+........+20

1×2+2×2+2×3+.........+2×10

2(1+2+3+.........+10)

2×10×4÷2

2×10×2

2×20