A

Vì Đ1 // Đ2    ( do  \(U_1=U_2\))

Nên \(I=I_1+I_2\)

\(I=0,1A+0,2A\)

\(I=0,3A\)

\(A=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{999}-\dfrac{1}{1000}\)

\(A=1-\dfrac{1}{1000}\)

\(A=\dfrac{999}{1000}\)

A

A

:))

\(\dfrac{x+1}{3}=\dfrac{3}{9}=>\left(x+1\right).9=3.3\)

\(\left(x+1\right).9=9=>x+1=1\)

=> x=0

#flo2k9 :)?