Question

2x-5=1

2x(x+2)-3(x+2)=0

5/x-3  +

-4/x+3=x-5/x^2-9

Answer 1

a) \(2x-5=1\)

\(\Leftrightarrow2x=1+5\)

\(\Leftrightarrow2x=6\)

\(\Leftrightarrow x=3\)

Vậy S = {3}

b) \(2x\left(x+2\right)-3\left(x+2\right)=0\)

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

\(\Leftrightarrow x+2=0;2x-3=0\)

*) \(x+2=0\)

\(x=-2\)

*) \(2x-3=0\)

\(2x=3\)

\(x=\dfrac{3}{2}\)

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

Answer 2

Giúp mk với

 

Answer 3

\(\dfrac{-4}{x+3}=\dfrac{x-5}{x^2-9}\) (1)

ĐKXĐ: \(x\ne3;x\ne-3\)

(1) \(\Leftrightarrow\dfrac{-4\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}=\dfrac{x-5}{\left(x+3\right)\left(x-3\right)}\)

\(\Leftrightarrow-4x+12=x-5\)

\(\Leftrightarrow-4x-x=-5-12\)

\(\Leftrightarrow-5x=-17\)

\(\Leftrightarrow x=\dfrac{17}{5}\) (nhận)

Vậy \(S=\left\{\dfrac{17}{5}\right\}\)