Question

[Trương Trí Dũng]

giúp mình với

PLS

Answer 1

[Yen Nhi]

Answer:

\(A=\frac{3x}{x+2}+\frac{6}{x+2}\) \(\left(ĐK:x\ne-2\right)\)

\(=\frac{3x+6}{x+2}\)

\(=\frac{3\left(x+2\right)}{x+2}\)

\(=3\)

\(B=\frac{x+1}{x-2}+\frac{x}{x+2}\) \(\left(ĐKXĐ:x\ne\pm2\right)\)

\(=\frac{\left(x+1\right)\left(x+2\right)}{\left(x-2\right)\left(x+2\right)}+\frac{x\left(x-2\right)}{\left(x-2\right)\left(x+2\right)}\)

\(=\frac{x^2+2x+x+2}{\left(x-2\right)\left(x+2\right)}+\frac{x^2-2x}{\left(x-2\right)\left(x+2\right)}\)

\(=\frac{x^2+3x+2+x^2-2x}{\left(x-2\right)\left(x+2\right)}\)

\(=\frac{\left(x^2+x^2\right)+\left(3x-2x\right)+2}{\left(x-2\right)\left(x+2\right)}\)

\(=\frac{2x^2+x+2}{\left(x-2\right)\left(x+2\right)}\)

\(=\frac{2x^2+x+2}{x^2-4}\)

\(C=\frac{2x-1}{x-3}+\frac{x}{x+3}+\frac{5-x-3x^2}{x^2-9}\) \(\left(ĐKXĐ:x\ne\pm3\right)\)

\(=\frac{\left(2x-1\right)\left(x+3\right)+x\left(x-3\right)+5-x-3x^2}{\left(x-3\right)\left(x+3\right)}\)

\(=\frac{2x^2-x+6x-3+x^2-3x+5-x-3x^2}{\left(x-3\right)\left(x+3\right)}\)

\(=\frac{x+2}{\left(x-3\right)\left(x+3\right)}\)