\(A=\left(5x\right)^2-10x+1+\left(3y\right)^2+10\)

\(=\left(5x-1\right)^2+\left(3y\right)^2+10\)

\(\Leftrightarrow Min_A=10\Leftrightarrow\hept{\begin{cases}x=\frac{1}{5}\\y=0\end{cases}}\)

\(B=\left(x+1\right)\left(x-2\right)\left(x-3\right)\left(x-6\right)\)

\(=\left[\left(x+1\right)\left(x-6\right)\right]\left[\left(x-2\right)\left(x-3\right)\right]\)

\(=\left(x^2-5x-6\right)\left(x^2-5x+6\right)\)

\(=\left(x^2-5x\right)^2-36\)

\(=\left[x^2\left(x-5\right)^2\right]-36\)

\(\Leftrightarrow Min_B=-36\Leftrightarrow\orbr{\begin{cases}x=0\\x=5\end{cases}}\)

Vậy ...

35 x  12 + 65 x 13

= 35 x 12 + 65 x (12 + 1)

= 35 x 12 + 65 x 12 + 65

= 12 x (65 + 35) + 65

= 12 x 100 + 65

= 1265

sách lớp mấy 

1. People shouldn't break things at Tet in my country.

2. People should make their house look more beautiful at Tet.

3. Tet is the busiest time of the year.

4. Tet is time for the family gatherings.

He like behaving well at tet.

                  \(x^2+xy-2008x-2009y-2010=0\)

\(\Leftrightarrow\)\(x^2+xy+x-2009x-2009y-2009=1\)

\(\Leftrightarrow\)        \(x\left(x+y+1\right)-2009\left(x+y+1\right)=1\)

\(\Leftrightarrow\)                           \(\left(x-2009\right)\left(x+y+1\right)=1\)

\(\Rightarrow\)\(\left(x-2009\right)=1\)và  \(\left(x+y+1\right)=1\)\(\Rightarrow\)\(x=2010;y=-2010\)

và     \(\left(x-2009\right)=-1\) và \(\left(x+y+1\right)=-1\)\(\Rightarrow\)\(x=2008;y=-2010\).

x^4=6.25^2

\(\Leftrightarrow\)x=\(\sqrt{6.25}\)

\(\Leftrightarrow\)x=-2.5

cậu làm kiểu gì mà đẹp quá zậy