\(\frac{2x+3}{2x+1}-\frac{2x+5}{2x+7}=\frac{1-6x^2+9x-9}{\left(2x+1\right)\left(2x+7\right)}\)
\(\Leftrightarrow\frac{\left(2x+3\right)\left(2x+7\right)-\left(2x+5\right)\left(2x-1\right)}{\left(2x+1\right)\left(2x+7\right)}=\frac{1-6x^2+9x-9}{\left(2x+1\right)\left(2x+7\right)}\)
\(\Rightarrow\left(2x+3\right)\left(2x+7\right)-\left(2x+5\right)\left(2x+1\right)=1-6x^2+9x-9\)
\(\Leftrightarrow4x^2+20x+21-4x^2-12x-5=1-6x^2+9x-9\)
\(\Leftrightarrow8x-16=1-6x^2+9x-9\)
\(\Leftrightarrow8x-16-1+6x^2-9x+9=0\)
\(\Leftrightarrow6x^2-x-8=0\)
Tự làm nốt nha
Trl
-Bạn chuyên toán thcs làm đúng r nhé !~
Học tốt
nhé bạn ~
\(\frac{2x+3}{2x+1}-\frac{2x+5}{2x+7}=1-\frac{6x^2+9x-9}{\left(2x+1\right)\left(2x+7\right)}\)
\(\Leftrightarrow\frac{\left(2x+3\right)\left(2x+7\right)-\left(2x+5\right)\left(2x+1\right)}{\left(2x+1\right)\left(2x+7\right)}=\frac{\left(2x+7\right)-6x^2-9x+9}{\left(2x+1\right)\left(2x+7\right)}\)
\(\Rightarrow4x^2+20x+21-4x^2-12x-5=2x+7-6x^2-9x+9\)
\(\Leftrightarrow8x+16=-6x^2-7x+16\)
\(\Leftrightarrow6x^2+7x+8x=0\)
\(\Leftrightarrow6x^2+15x=0\)
\(\Leftrightarrow x\left(6x+15\right)=0\)
Đến đây tự làm nốt nha
hok tốt
