\(\left(x+2\right)\left(-4\right)=0\\ \Rightarrow x+2=0\\ \Rightarrow x=-2\)

\(1475+203-475+1797\\ =\left(1475-475\right)+\left(1797+203\right)\\ =1000+2000\\ =3000\)

\(X:12=406\\ X=406\times12=4872\)

\(C\)

CM căn 2 là số vô tỉ

G/s căn 2 là số hữu tỉ có dạng \(\dfrac{m}{n}\left(m,n\right)=1\)

\(\Rightarrow\sqrt{2}=\dfrac{m}{n}\\ \Rightarrow2=\dfrac{m^2}{n^2}\Rightarrow m^2=2n^2\\ \Rightarrow m^2⋮2\\ \Rightarrow m^2⋮4\Rightarrow2n^2⋮4\Rightarrow n^2⋮2\Rightarrow n⋮2\)

Do \(m⋮2;n⋮2\)

Vậy giả sử sai =>(đpcm)

B

0,16 \(m^2\)

\(\left(2+x\right)^3-23=41\\ \left(2+x\right)^3=64\\ 2+x=4\\ x=2\)

\(\dfrac{1}{2x-3}+\dfrac{1}{2x+3}=\dfrac{2x+4}{4x^2-9}\)

\(\dfrac{2x+3+2x-3}{\left(2x-3\right)\left(2x+3\right)}=\dfrac{2x+4}{4x^2-9}\)

\(\dfrac{4x}{4x^2-9}=\dfrac{2x+4}{4x^2-9}\Rightarrow4x=2x+4\)

\(\Rightarrow2x=4\Rightarrow x=2\)

\(A=1+2+2^2+...+2^{2020}+2^{2021}\\ \Rightarrow2A=2+2^2+2^3+...+2^{2021}+2^{2022}\\ \Rightarrow2A-A=A=2^{2022}-1\)

Vậy \(A\) và \(B\) là 2 số tự nhiên liên tiếp.