Question

cho 2 biểu thức A = \(\dfrac{5}{2m+1}\) và B =\(\dfrac{4}{2m-1}\) Biết 2A +3B = 0 tìm m

Answer 1

ta có : \(2A+3B=0\) \(\Leftrightarrow2.\dfrac{5}{2m+1}+3.\dfrac{4}{2m-1}=0\)

\(\Leftrightarrow\dfrac{10}{2m+1}+\dfrac{12}{2m-1}=0\Leftrightarrow\dfrac{10\left(2m-1\right)+12\left(2m+1\right)}{\left(2m-1\right)\left(2m+1\right)}=0\)

\(\Rightarrow10\left(2m-1\right)+12\left(2m+1\right)=0\Leftrightarrow20m-10+24m+12=0\)

\(\Leftrightarrow44m+2=0\Leftrightarrow44m=-2\Leftrightarrow m=\dfrac{-2}{44}=\dfrac{-1}{22}\) vậy \(m=\dfrac{-1}{22}\)