Question

помогите пожалуйста по действиям

Answer 1

$\frac{n+21}{16-8n+ n^{2} }- \frac{n+3}{16- n^{2} }= \frac{n+21}{(4-n) ^{2} }- \frac{n+3}{(4-n)(4+n)}= \frac{4n+ n^{2} +21n+84-4n-12+ n^{2} +3n}{(4-n) ^{2}(4+n) }$$= \frac{2 n^{2}+24n+72 }{(4-n) ^{2}(4+n) } = \frac{ n^{2}+12n+36 }{(4-n) ^{2}(4+n) }= \frac{(n+6) ^{2} }{(4-n) ^{2}(4+n) }$


$(\frac{n-4}{n+6}) ^{2}* \frac{(n+6) ^{2} }{(n-4) ^{2}(n+4) }= \frac{(n-4) ^{2} }{(n+6) ^{2} }* \frac{(n+6) ^{2} }{(n-4) ^{2}(n+4) } = \frac{1}{n+4}$


$\frac{3n+10}{n+4}+ \frac{1}{n+4}= \frac{3n+10+1}{n+4}= \frac{3n+11}{n+4}$