Ответы
Ответ дал:
0
155.
б)
![frac{xy-1.2y^2}{x^2-1.2xy} + frac{x^2+0.4xy}{xy+0.4y^2} = frac{y(x-1.2y)}{x(x-1.2y)} + frac{x(x+0.4y)}{y(x+0.4y)} = frac{y} {x}+ frac{x}{y}= frac{x^2+y^2}{xy} frac{xy-1.2y^2}{x^2-1.2xy} + frac{x^2+0.4xy}{xy+0.4y^2} = frac{y(x-1.2y)}{x(x-1.2y)} + frac{x(x+0.4y)}{y(x+0.4y)} = frac{y} {x}+ frac{x}{y}= frac{x^2+y^2}{xy}](https://tex.z-dn.net/?f=+frac%7Bxy-1.2y%5E2%7D%7Bx%5E2-1.2xy%7D+%2B+frac%7Bx%5E2%2B0.4xy%7D%7Bxy%2B0.4y%5E2%7D+%3D+frac%7By%28x-1.2y%29%7D%7Bx%28x-1.2y%29%7D+%2B+frac%7Bx%28x%2B0.4y%29%7D%7By%28x%2B0.4y%29%7D+%3D+frac%7By%7D+%7Bx%7D%2B+frac%7Bx%7D%7By%7D%3D+frac%7Bx%5E2%2By%5E2%7D%7Bxy%7D+)
г) смотри скан, возможно, я где-то ошиблась, т.к. длинновата концовка
156
а)
![frac{1}{(a-b)(a-c)}+ frac{1}{(b-c)(b-a)}+ frac{1}{(c-a)(c-b)}= \ frac{1}{(a-b)(a-c)}- frac{1}{(b-c)(a-b)}-frac{1}{(a-c)(c-b)}= \ frac{1}{(a-b)(a-c)}- frac{1}{(b-c)(a-b)}+frac{1}{(a-c)(b-c)}= \ frac{b-c}{(a-b)(a-c)(b-c)}- frac{a-c}{(a-b)(a-c)(b-c)}+frac{a-b}{(a-b)(a-c)(b-c)}= \ frac{b-c-a+c+a-b}{(a-b)(a-c)(b-c)}= frac{0}{(a-b)(a-c)(b-c)}= 0 frac{1}{(a-b)(a-c)}+ frac{1}{(b-c)(b-a)}+ frac{1}{(c-a)(c-b)}= \ frac{1}{(a-b)(a-c)}- frac{1}{(b-c)(a-b)}-frac{1}{(a-c)(c-b)}= \ frac{1}{(a-b)(a-c)}- frac{1}{(b-c)(a-b)}+frac{1}{(a-c)(b-c)}= \ frac{b-c}{(a-b)(a-c)(b-c)}- frac{a-c}{(a-b)(a-c)(b-c)}+frac{a-b}{(a-b)(a-c)(b-c)}= \ frac{b-c-a+c+a-b}{(a-b)(a-c)(b-c)}= frac{0}{(a-b)(a-c)(b-c)}= 0](https://tex.z-dn.net/?f=+frac%7B1%7D%7B%28a-b%29%28a-c%29%7D%2B+frac%7B1%7D%7B%28b-c%29%28b-a%29%7D%2B+frac%7B1%7D%7B%28c-a%29%28c-b%29%7D%3D+++%5C++frac%7B1%7D%7B%28a-b%29%28a-c%29%7D-+frac%7B1%7D%7B%28b-c%29%28a-b%29%7D-frac%7B1%7D%7B%28a-c%29%28c-b%29%7D%3D++++%5C++frac%7B1%7D%7B%28a-b%29%28a-c%29%7D-+frac%7B1%7D%7B%28b-c%29%28a-b%29%7D%2Bfrac%7B1%7D%7B%28a-c%29%28b-c%29%7D%3D++++%5C++frac%7Bb-c%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D-+frac%7Ba-c%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%2Bfrac%7Ba-b%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%3D++++%5C++frac%7Bb-c-a%2Bc%2Ba-b%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%3D+++frac%7B0%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%3D+++0)
б)
в)
![frac{a^2}{(a-b)(a-c)}+ frac{b^2}{(b-c)(b-a)}+ frac{c^2}{(c-a)(c-b)}= \ frac{a^2}{(a-b)(a-c)}- frac{b^2}{(b-c)(a-b)}-frac{c^2}{(a-c)(c-b)}= \ frac{a^2}{(a-b)(a-c)}- frac{b^2}{(b-c)(a-b)}+frac{c^2}{(a-c)(b-c)}= \ frac{a^2(b-c)}{(a-b)(a-c)(b-c)}- frac{b^2(a-c)}{(a-b)(a-c)(b-c)}+frac{c^2(a-b)}{(a-b)(a-c)(b-c)}= \ frac{a^2(b-c)-b^2(a-c)+c^2(a-b)}{(a-b)(a-c)(b-c)}=frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{(a-b)(a-c)(b-c)}= \ frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{(a^2-ac-ab+bc)(b-c)}= \ frac{a^2}{(a-b)(a-c)}+ frac{b^2}{(b-c)(b-a)}+ frac{c^2}{(c-a)(c-b)}= \ frac{a^2}{(a-b)(a-c)}- frac{b^2}{(b-c)(a-b)}-frac{c^2}{(a-c)(c-b)}= \ frac{a^2}{(a-b)(a-c)}- frac{b^2}{(b-c)(a-b)}+frac{c^2}{(a-c)(b-c)}= \ frac{a^2(b-c)}{(a-b)(a-c)(b-c)}- frac{b^2(a-c)}{(a-b)(a-c)(b-c)}+frac{c^2(a-b)}{(a-b)(a-c)(b-c)}= \ frac{a^2(b-c)-b^2(a-c)+c^2(a-b)}{(a-b)(a-c)(b-c)}=frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{(a-b)(a-c)(b-c)}= \ frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{(a^2-ac-ab+bc)(b-c)}= \](https://tex.z-dn.net/?f=frac%7Ba%5E2%7D%7B%28a-b%29%28a-c%29%7D%2B+frac%7Bb%5E2%7D%7B%28b-c%29%28b-a%29%7D%2B+frac%7Bc%5E2%7D%7B%28c-a%29%28c-b%29%7D%3D+%5C+frac%7Ba%5E2%7D%7B%28a-b%29%28a-c%29%7D-+frac%7Bb%5E2%7D%7B%28b-c%29%28a-b%29%7D-frac%7Bc%5E2%7D%7B%28a-c%29%28c-b%29%7D%3D+%5C+frac%7Ba%5E2%7D%7B%28a-b%29%28a-c%29%7D-+frac%7Bb%5E2%7D%7B%28b-c%29%28a-b%29%7D%2Bfrac%7Bc%5E2%7D%7B%28a-c%29%28b-c%29%7D%3D+%5C+frac%7Ba%5E2%28b-c%29%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D-+frac%7Bb%5E2%28a-c%29%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%2Bfrac%7Bc%5E2%28a-b%29%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%3D+%5C+frac%7Ba%5E2%28b-c%29-b%5E2%28a-c%29%2Bc%5E2%28a-b%29%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%3Dfrac%7Ba%5E2b-a%5E2c-ab%5E2%2Bb%5E2c%2Bac%5E2-bc%5E2%7D%7B%28a-b%29%28a-c%29%28b-c%29%7D%3D+%5C+frac%7Ba%5E2b-a%5E2c-ab%5E2%2Bb%5E2c%2Bac%5E2-bc%5E2%7D%7B%28a%5E2-ac-ab%2Bbc%29%28b-c%29%7D%3D+%5C)
![frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{a^2b-a^2c-abc+ac^2-ab^2+abc+b^2c-bc^2}= \ frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{a^2b-a^2c+ac^2-ab^2+b^2c-bc^2} \ frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}=1 frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{a^2b-a^2c-abc+ac^2-ab^2+abc+b^2c-bc^2}= \ frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{a^2b-a^2c+ac^2-ab^2+b^2c-bc^2} \ frac{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}{a^2b-a^2c-ab^2+b^2c+ac^2-bc^2}=1](https://tex.z-dn.net/?f=+frac%7Ba%5E2b-a%5E2c-ab%5E2%2Bb%5E2c%2Bac%5E2-bc%5E2%7D%7Ba%5E2b-a%5E2c-abc%2Bac%5E2-ab%5E2%2Babc%2Bb%5E2c-bc%5E2%7D%3D+%5C+frac%7Ba%5E2b-a%5E2c-ab%5E2%2Bb%5E2c%2Bac%5E2-bc%5E2%7D%7Ba%5E2b-a%5E2c%2Bac%5E2-ab%5E2%2Bb%5E2c-bc%5E2%7D+%5C+frac%7Ba%5E2b-a%5E2c-ab%5E2%2Bb%5E2c%2Bac%5E2-bc%5E2%7D%7Ba%5E2b-a%5E2c-ab%5E2%2Bb%5E2c%2Bac%5E2-bc%5E2%7D%3D1)
б)
г) смотри скан, возможно, я где-то ошиблась, т.к. длинновата концовка
156
а)
б)
в)
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![](https://st.uroker.com/files/5ab/5ab705d10ea70cae407cf6ecea39b1a7.jpg)
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