\(\overrightarrow{AD}=\overrightarrow{AB}+\overrightarrow{BD}\)

\(\overrightarrow{BC}=\overrightarrow{BD}+\overrightarrow{DC}\)

Mà \(\overrightarrow{AB}=\overrightarrow{DC}\) (gt)

\(\Rightarrow\overrightarrow{AD}=\overrightarrow{BC}\)

\(A=\left\{0;2;4;6\right\},B=\left\{4;5;6\right\}\)

\(\left\{{}\begin{matrix}X=\left\{4;6\right\}\\Y=\left\{0;2\right\}\end{matrix}\right.;\left\{{}\begin{matrix}X=\left\{2;4;6\right\}\\Y=\left\{0\right\}\end{matrix}\right.;\left\{{}\begin{matrix}X=\left\{0;4;6\right\}\\Y=\left\{2\right\}\end{matrix}\right.\)

\(P=\left\{4;6\right\};\left\{4;6;0\right\};\left\{4;6;2\right\};\left\{4;6;5\right\};\left\{4;6;0;2\right\};\left\{4;6;0;5\right\};\left\{4;6;2;5\right\};\left\{0;2;4;5;6\right\}\)

\(A=\left\{-2;-1;0;1;2;3;4;5\right\}\)

\(B=\left\{-2;2;-3;3;-4;4;-5;5\right\}\)

\(C=\left\{1;2\right\}\)

2)

a)\(\overrightarrow{AB}+\overrightarrow{BC}+\overrightarrow{CD}=\overrightarrow{AE}-\overrightarrow{DE}\Leftrightarrow\overrightarrow{AD}=\overrightarrow{AE}+\overrightarrow{ED}\Leftrightarrow\overrightarrow{AD}=\overrightarrow{AD}\)

b)

\(\overrightarrow{AB}+\overrightarrow{BC}+\overrightarrow{CD}+\overrightarrow{DA}=\overrightarrow{0}\Leftrightarrow\overrightarrow{AA}=\overrightarrow{0}\)

c)

\(\overrightarrow{DA}-\overrightarrow{CA}=\overrightarrow{DB}-\overrightarrow{CB}\Leftrightarrow\overrightarrow{DA}+\overrightarrow{AC}=\overrightarrow{DB}+\overrightarrow{BC}\Leftrightarrow\overrightarrow{DC}=\overrightarrow{DC}\)

d)\(\overrightarrow{AC}+\overrightarrow{DA}+\overrightarrow{BD}=\overrightarrow{AD}-\overrightarrow{CD}+\overrightarrow{BA}\Leftrightarrow\overrightarrow{AC}+\overrightarrow{CD}+\overrightarrow{DA}-\overrightarrow{BA}+\overrightarrow{BD}-\overrightarrow{AD}=\overrightarrow{0}\Leftrightarrow\overrightarrow{AC}+\overrightarrow{CD}+\overrightarrow{DA}+\overrightarrow{AB}+\overrightarrow{BD}+\overrightarrow{DA}=\overrightarrow{0}\Leftrightarrow\overrightarrow{AA}=\overrightarrow{0}\)

Rewrite each sentences so that the meaning stays the same.( passive )

People say Mr Clark was difficult to work with when he was young.

-> Mr Clark ........................................................................................

At least 130 000 dolphins are reported to be caught in the nets of tuna fishers every year.

-> It is ...................................................................................

John gave a bar of chocolate to Jill.

->

->

Note: The third sentence you will change it to passive for two ways.

Tomorrow, I will study it. Helps me, please. ( 25/09 )

Ta có:

\(\dfrac{21x^5y^6}{-56x^3y^7}=\dfrac{3.7.x^3.x^2.y^6}{-8.7.x^3.y^6.y^1}=\dfrac{3x^2}{-8y}\)

\(x^3y^4-5y^8+x^3y^4+x^3-y^2-xy^4+5y^8\)

Rút gọn:

\(\left(-5y^8+5y^8\right)+\left(x^3y^4+x^3y^4\right)-xy^4+x^3-y^2\)

\(=2x^3y^4-xy^4+x^3-y^2\)

Bậc của đa thức là 7