Алгебра, вопрос задал queen666w , 1 год назад

# 6.78

#2,3,4

помогите срочно!

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Ответил сок111213
0

2)

(x -  \frac{x + y}{x - y}  + y) \div (1 -  \frac{2y + 1}{ {x}^{2} -  {y}^{2}  } ) =  \\  = ( \frac{x(x - y) - (x + y) + y(x - y)}{x - y} ) \times ( \frac{(x - y)(x + y)}{( {x}^{2}  -  {y}^{2}  - (2y + 1)} ) =  \\  = ( \frac{ {x}^{2} - xy - x - y + xy -  {y}^{2}  }{x - y} ) \times ( \frac{(x - y)(x + y)}{ {x}^{2}  -  {y}^{2}  -2 y - 1} ) =  \\  =  \frac{(x - y)(x + y) - (x + y)}{x - y}  \times  \frac{(x - y)(x + y)}{ {x}^{2}  - (y + 1) {}^{2} }  =  \\  =  (x - y - 1)(x + y) \times  \frac{(x + y)}{(x + y + 1)(x - y - 1)}  =  \\  =  \frac{(x + y) {}^{2} }{x + y + 1}  =  \frac{ {x}^{2} + 2xy +  {y}^{2}  }{x + y + 1}

3)

 \frac{x - 1}{x}  \times  \frac{x + 1}{x}  \times  \frac{ {x}^{2} + 1 }{ {x}^{2} }  \times  \frac{ {x}^{4} }{ {x}^{4} - 1 }  =  \\  =  \frac{ {x}^{4} (x - 1)(x + 1)( {x}^{2} + 1) }{ {x}^{4} (x {}^{2}  - 1)( {x}^{2} + 1) }  =  \frac{(x - 1)(x + 1)}{(x - 1)(x + 1)}  = 1

4)

(( \frac{1 - a}{a}  \div  \frac{a}{1 + a} ) \div  \frac{ {a}^{2} }{1 +  {a}^{2} } ) \div  \frac{ {a}^{4} - 1 }{ {a}^{4} }  =  \\  = \frac{(1 - a)(1 + a)}{a \times a}  \times  \frac{(1 +  {a}^{2}) }{ {a}^{2} }  \times  \frac{ {a}^{4} }{( {a}^{2}  - 1)( {a}^{2}  + 1)}  =  \\  =  \frac{(1 - a)(1 + a)}{ {a}^{2} - 1}  =  \frac{ - (a - 1)(1 + a)}{(a - 1)(a + 1)}  =  - 1

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