a) \(\frac{3x-2}{2xy}-\frac{7x-4}{2xy}\)
\(=\frac{3x-2}{2xy}+\frac{-\left(7x-4\right)}{2xy}\)
\(=\frac{3x-2-7x+4}{2xy}\)
\(=\frac{-4x+2}{2xy}\)
\(=\frac{2.\left(-2x+1\right)}{2xy}.\)
\(=\frac{-2x+1}{xy}.\)
b) \(\frac{6}{x^2+4x}+\frac{3}{2x+8}\)
Ta có:
\(x^2+4x=x.\left(x+4\right)\)
\(2x+8=2.\left(x+4\right)\)
\(MTC:2x.\left(x+4\right)\)
\(\frac{6}{x^2+4x}+\frac{3}{2x+8}\)
\(=\frac{6}{x.\left(x+4\right)}+\frac{3}{2.\left(x+4\right)}\)
\(=\frac{6.2}{2x.\left(x+4\right)}+\frac{3x}{2x.\left(x+4\right)}\)
\(=\frac{12}{2x.\left(x+4\right)}+\frac{3x}{2x.\left(x+4\right)}\)
\(=\frac{12+3x}{2x.\left(x+4\right)}\)
\(=\frac{3.\left(4+x\right)}{2x.\left(x+4\right)}\)
\(=\frac{3.\left(x+4\right)}{2x.\left(x+4\right)}\)
\(=\frac{3}{2x}.\)
Chúc bạn học tốt!