\(\Leftrightarrow3x^2+9x-x-3-\left(2x^2-2x+5x-5\right)-8=x^2+2x-3\)
\(\Leftrightarrow3x^2+8x-3-2x^2-3x+5-8-x^2-2x+3=0\)
=>3x=8
hay x=8/3
c) \(\dfrac{3x-1}{x-1}-\dfrac{2x+5}{x+3}-\dfrac{8}{x^2+2x-3}=1\)
\(\Leftrightarrow\dfrac{3x-1}{x-1}-\dfrac{2x+5}{x+3}-\dfrac{8}{x^2-1x+3x-3}=1\)
\(\Leftrightarrow\dfrac{3x-1}{x-1}-\dfrac{2x+5}{x+3}-\dfrac{8}{x\left(x-1\right)+3\left(x-1\right)}=1\)
\(\Leftrightarrow\dfrac{\left(x+3\right)\left(3x-1\right)}{\left(x-1\right)\left(x+3\right)}-\dfrac{\left(x-1\right)\left(2x+5\right)}{\left(x-1\right)\left(x+3\right)}-\dfrac{8}{\left(x+3\right)\left(x-1\right)}=1\)
\(\Leftrightarrow\left(x+3\right)\left(3x-1\right)-\left(x-1\right)\left(2x+5\right)-8-1=0\)
\(\Leftrightarrow3x^2-x+9x-3-\left(2x^2+5x-2x-5\right)-9=0\)
\(\Leftrightarrow3x^2-x+9x-3-2x^2-5x+2x+5-9=0\)
\(\Leftrightarrow\left(3x^2-2x^2\right)+\left(-x+9x-5x+2x\right)+\left(-3+5-9\right)=0\)
\(\Leftrightarrow x^2+5x-7=0\)
còn lại bạn tham khảo ở đây nhé: https://hoc24.vn/cau-hoi/x2-5x-7-0.260367740520
Kết luận: x vô nghiệm.
. Ta có:
