Question

решите пожалуйста даю 5 звезд ​

Answer 1

Ответ:

$\dfrac{x+10}{5-x} \ ;$

$\dfrac{3-a}{a+6} \ ;$

Объяснение:

$\bigg (\dfrac{x}{x^{2}-25}+\dfrac{5}{5-x}+\dfrac{1}{x+5} \bigg ): \bigg (x-5+\dfrac{28-x^{2}}{x+5} \bigg )=\bigg (\dfrac{x}{(x-5)(x+5)}-\dfrac{5}{x-5}+$

$+\dfrac{1}{x+5} \bigg ):\dfrac{(x-5)(x+5)+28-x^{2}}{x+5}=\dfrac{x-5(x+5)+(x-5)}{(x-5)(x+5)}:\dfrac{x^{2}-25+28-x^{2}}{x+5}=$

$=\dfrac{x-5x-25+x-5}{(x-5)(x+5)}:\dfrac{3}{x+5}=\dfrac{-3x-30}{(x-5)(x+5)}:\dfrac{3}{x+5}=\dfrac{-3(x+10)}{(x-5)(x+5)}:$

$:\dfrac{3}{x+5}=\dfrac{3(x+10)}{(5-x)(x+5)} \cdot \dfrac{x+5}{3}=\dfrac{3 \cdot (x+10) \cdot (x+5)}{(5-x) \cdot (x+5) \cdot 3}=\dfrac{x+10}{5-x} \ ;$

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$\bigg (\dfrac{12-a^{2}}{a+3}+a-3 \bigg ): \bigg (\dfrac{1}{a+3}+\dfrac{a}{a^{2}-9}+\dfrac{5}{3-a} \bigg )=\dfrac{12-a^{2}+(a-3)(a+3)}{a+3}:$

$: \bigg (\dfrac{1}{a+3}+\dfrac{a}{(a+3)(a-3)}-\dfrac{5}{a-3} \bigg )=\dfrac{12-a^{2}+a^{2}-9}{a+3}:\dfrac{a-3+a-5(a+3)}{(a+3)(a-3)}=$

$=\dfrac{3}{a+3}:\dfrac{2a-3-5a-15}{(a+3)(a-3)}=\dfrac{3}{a+3}:\dfrac{-3a-18}{(a+3)(a-3)}=\dfrac{3}{a+3}:\dfrac{-3(a+6)}{(a+3)(a-3)}=$

$=\dfrac{3}{a+3}:\dfrac{3(a+6)}{(a+3)(3-a)}=\dfrac{3}{a+3} \cdot \dfrac{(a+3)(3-a)}{3(a+6)}=\dfrac{3 \cdot (a+3) \cdot (3-a)}{3 \cdot (a+3)(a+6)}=$

$=\dfrac{3-a}{a+6} \ ;$