Số hs nữ chiếm số phần trăm :

15 : 30 x 100 =  50%

\(=-\dfrac{5}{7}\times\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{5}{7}=-\dfrac{5}{7}+\dfrac{5}{7}=0\)

chắc có :v

\(4x^2-1=\left(x-5\right)\left(1-2x\right)\)

\(\Leftrightarrow4x^2-1=x-2x^2-5+10x\)

\(\Leftrightarrow6x^2-11x+4=0\)

\(\Leftrightarrow6x^2-8x-3x+4=0\)

\(\Leftrightarrow2x\left(3x-4\right)-1\left(3x-4\right)=0\)

\(\Leftrightarrow\left(3x-4\right)\left(2x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{4}{3}\\x=\dfrac{1}{2}\end{matrix}\right.\)

2,340623173

\(=14,35\times\left(2+8\right)=143,5\)

r

960 phút

40 phút

A