Question

tìm x biết :

a. \(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x+1}\)

b. \(\dfrac{x+1}{2x+1}=\dfrac{0,5x+2}{x+3}\)

Answer 1

\(\dfrac{3x+2}{5x-7}=\dfrac{3x-1}{5x+1}\)

\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x-7\right)\)

\(\Leftrightarrow15x^2+3x+10x+2=15x^2-21x-5x-7\)

\(\Leftrightarrow15x^2+13x+2=15x^2-26x-7\)

\(\Leftrightarrow15x^2-15x^2-13x-2=26x-7\)

\(\Leftrightarrow-13x-2=26x-7\)

\(\Leftrightarrow26x+13x=7+2\)

\(\Leftrightarrow39x=9\Leftrightarrow x=\dfrac{3}{13}\)

b tương tự