Question

Ma puteti ajuta va rog​

Answer 1

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

2(1+2+3+...+10)-(10×20/2)

2(10×11/2)-(10×10)

2×55-100

110-100

10

Answer 2

Răspuns: 10

Explicație pas cu pas:

(2+4+6+...+20)-(1+3+5+...+19)=10

[2×(1+2+3+...+10)]-[(1+2+3+...+19)-(2+4+6+...+18)]=10

{2×[10×(10+1)÷2]}-{[19×(19+1)÷2]-2×(1+2+3+...+9)}=10

[2×(10×11÷2)]-{(19×20÷2)-2×[9×(9+1)÷2]}=10

[2×(110÷2)]-[(380÷2)-2×(9×10÷2)]=10

(2×55)-[190-2×(90÷2)]=10

110-(190-2×45)=10

110-(190-90)=10

110-100=10