30)
MTC: (2x+1)(2x-1)
\(\dfrac{3x-1}{2x+1}=\dfrac{\left(3x-1\right)\left(2x-1\right)}{\left(2x+1\right)\left(2x-1\right)}\)
\(\dfrac{6}{2x-1}=\dfrac{6\left(2x+1\right)}{\left(2x+1\right)\left(2x-1\right)}\)
31)
MT1: 2x-4=2(x-2)
MT2: x2-4=(x-2)(x+2)
=>MTC:2(x-2)(x+2)
\(\dfrac{7x}{2x-4}=\dfrac{7x}{2\left(x-2\right)}=\dfrac{7x\left(x+2\right)}{2\left(x-2\right)\left(x+2\right)}\)
\(\dfrac{2x+3}{x^2-4}=\dfrac{2x+3}{\left(x-2\right)\left(x+2\right)}=\dfrac{2\left(2x+3\right)}{2\left(x-2\right)\left(x+2\right)}\)