Cân kiệm liêm chính

I would buy this dress if it fitted me

touch

If she saw him every day,she couldn't do anything

=> CT: If (loại 2)

If QKĐ,Could(not) + V1

\(\dfrac{3}{4}\times\dfrac{13}{12}=\dfrac{13}{16}\)

\(9x^2-1=\left(3x+1\right)\left(4x+1\right)\)

\(\Leftrightarrow\left(3x-1\right)\left(3x+1\right)=\left(3x+1\right)\left(4x+1\right)\)

\(\Leftrightarrow\left(3x-1\right)\left(3x+1\right)-\left(3x+1\right)\left(4x+1\right)=0\)

\(\Leftrightarrow\left(3x+1\right)\left(3x-1-4x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x+1=0\\-x-2=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}3x=-1\\-x=2\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-1}{3}\\x=-2\end{matrix}\right.\)

Vậy \(S=\left\{-\dfrac{1}{3};-2\right\}\)

+ Không có CN và TN

+ VN : chơi kéo co

B.\(i=\dfrac{n_1}{n_2}=\dfrac{D_1}{D_2}\)