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\(\left(\frac{4}{x-4}-\frac{4}{x+4}\right)\times\frac{x^2+8x+16}{32}\)
ĐKXĐ : \(x\ne\pm4\)
\(=\left(\frac{4\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}-\frac{4\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}\right)\times\frac{\left(x+4\right)^2}{32}\)
\(=\left(\frac{4x+16-4x+16}{\left(x-4\right)\left(x+4\right)}\right)\times\frac{\left(x+4\right)^2}{32}\)
\(=\frac{32}{\left(x-4\right)\left(x+4\right)}\times\frac{\left(x+4\right)^2}{32}\)
\(=\frac{x+4}{x-4}\)
\(\left(\frac{4}{x-4}-\frac{4}{x+4}\right).\frac{x^2+8x+16}{32}\)
\(=\left(\frac{4\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}-\frac{4\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}\right).\frac{\left(x+4\right)^2}{32}\)
\(=\frac{4x+16-4x+16}{\left(x-4\right)\left(x+4\right)}.\frac{\left(x+4\right)^2}{32}=\frac{32}{\left(x-4\right)\left(x+4\right)}.\frac{\left(x+4\right)^2}{32}=\frac{x+4}{x-4}\)
\(=\dfrac{x^2-4y}{xy}\cdot\dfrac{x^2}{x-y}=\dfrac{x\left(x^2-4y\right)}{y\left(x-y\right)}\)
ĐKXĐ: \(x\ne4\)
\(\dfrac{16-x^2}{4-x}\) \(=\dfrac{\left(4-x\right)\left(4+x\right)}{4-x}\) \(=4+x\)