a)
\(\frac{32x-8x^2+2x^3}{x^3+64}=\frac{2x.\left(16-4x+x^2\right)}{x^3+4^3}=\frac{2x.\left(16-4x+x^2\right)}{\left(x+4\right).\left(x^2-4x+16\right)}=\frac{2x.\left(x^2-4x+16\right)}{\left(x+4\right).\left(x^2-4x+16\right)}=\frac{2x}{x+4}.\)
b)
\(\frac{5x^3+5x}{x^4-1}=\frac{5x.\left(x^2+1\right)}{\left(x^2\right)^2-1}=\frac{5x.\left(x^2+1\right)}{\left(x^2-1\right).\left(x^2+1\right)}=\frac{5x}{x^2-1}.\)
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