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b)
$B= \mathop {\lim }\limits_{n\to \infty }\frac{(n+2)!+ (n+1)!}{ (n+2)!- (n+1)! }= \mathop {\lim }\limits_{n\to \infty }\frac{(n+1)!(n+2+1) }{ (n+1)!(n+2-1) } = \mathop {\lim }\limits_{n\to \infty }\frac{n+3 }{n+1 } = \mathop {\lim }\limits_{n\to \infty }\frac{1+\frac{3}{n} }{1+\frac{1}{n} } =1 $
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