giúp em câu 6,9,10 câu này khó em k làm dc
\(5,\Leftrightarrow8\left(x^2-5x+3x-15\right)-\left(8x^2-4x+20x-10\right)=0\)
\(\Leftrightarrow8x^2-40x+24x-120-8x^2+4x-20x+10=0\)
\(\Leftrightarrow-32x-110=0\)
\(\Leftrightarrow x=\dfrac{110}{-32}=-\dfrac{55}{16}\)
\(9,\Leftrightarrow\left(5x-5\right)\left(2x+7-2x-1\right)=x+2-x+5\)
\(\Leftrightarrow6\left(5x-5\right)=7\)
\(\Leftrightarrow5x-5=\dfrac{7}{6}\)
\(\Leftrightarrow x=\dfrac{37}{30}\)
\(8,\Leftrightarrow\left(6x-3\right)\left(x-5-3x+1\right)-3+13=0\)
\(\Leftrightarrow-6\left(2x-1\right)\left(x+2\right)+10=0\)
\(\Leftrightarrow2x^2-x+4x-2=\dfrac{10}{6}\)
\(\Leftrightarrow2x^2+3x-\dfrac{11}{3}=0\)
\(10,\Leftrightarrow8x\left(x^2+x+6x+6\right)-8x^3=5x\)
\(\Leftrightarrow8x^3+8x^2+48x^2+48x-8x^3-5x=0\)
\(\Leftrightarrow56x^2+43x=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{43}{56}\end{matrix}\right.\)
Vậy ....
;-; quên đọc đề may làm trúng 9; 10 câu 6 nốt đây nha
\(6,\Leftrightarrow9x^2-9x-8x^2+40-x^2=5x-3-7x+4\)
\(\Leftrightarrow9x^2-9x-8x^2+40-x^2-5x+3+7x-4=0\)
\(\Leftrightarrow-7x+39=0\)
\(\Leftrightarrow x=\dfrac{39}{7}\)
Vậy ...
