tính A=(x/x^2-25-x-5/x^2+ 5 x): (2 x-5/x^2+ 5 x) +x/5-x 29/07/2021 Bởi Arya tính A=(x/x^2-25-x-5/x^2+ 5 x): (2 x-5/x^2+ 5 x) +x/5-x
Đáp án: \[ – 1\] Giải thích các bước giải: Ta có: \(\begin{array}{l}A = \left( {\frac{x}{{{x^2} – 25}} – \frac{{x – 5}}{{{x^2} + 5x}}} \right):\left( {\frac{{2x – 5}}{{{x^2} + 5x}}} \right) + \frac{x}{{5 – x}}\\ = \left( {\frac{x}{{\left( {x – 5} \right)\left( {x + 5} \right)}} – \frac{{\left( {x – 5} \right)}}{{x\left( {x + 5} \right)}}} \right):\left( {\frac{{2x – 5}}{{x\left( {x + 5} \right)}}} \right) + \frac{x}{{5 – x}}\\ = \left( {\frac{{{x^2} – {{\left( {x – 5} \right)}^2}}}{{x\left( {x – 5} \right)\left( {x + 5} \right)}}} \right):\frac{{2x – 5}}{{x\left( {x + 5} \right)}} + \frac{x}{{5 – x}}\\ = \frac{{10x – 25}}{{x\left( {x – 5} \right)\left( {x + 5} \right)}}.\frac{{x\left( {x + 5} \right)}}{{2x – 5}} + \frac{x}{{5 – x}}\\ = \frac{5}{{x – 5}} – \frac{x}{{x – 5}}\\ = \frac{{5 – x}}{{x – 5}} = – 1\end{array}\) Bình luận
Đáp án: Giải thích các bước giải: $\color {orange } { A = ( \frac{x}{x ^ 2} – 25 – x – \frac{5}{x ^ 2} + 5x ) \div (2x – \frac{5}{x ^ 2} + 5x) + \frac{x}{5} – x \\\Leftrightarrow A = ( \frac{1}{x} – 25 – \frac{5}{x ^ 2 } + 4x) \div (7x + \frac{5}{x ^ 2}) + \frac{x}{5} – x \\\Leftrightarrow (7x + \frac{5}{x ^ 2})A = \frac{1}{x} – 25 – \frac{5}{x ^ 2} } $ Bình luận
Đáp án:
\[ – 1\]
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
A = \left( {\frac{x}{{{x^2} – 25}} – \frac{{x – 5}}{{{x^2} + 5x}}} \right):\left( {\frac{{2x – 5}}{{{x^2} + 5x}}} \right) + \frac{x}{{5 – x}}\\
= \left( {\frac{x}{{\left( {x – 5} \right)\left( {x + 5} \right)}} – \frac{{\left( {x – 5} \right)}}{{x\left( {x + 5} \right)}}} \right):\left( {\frac{{2x – 5}}{{x\left( {x + 5} \right)}}} \right) + \frac{x}{{5 – x}}\\
= \left( {\frac{{{x^2} – {{\left( {x – 5} \right)}^2}}}{{x\left( {x – 5} \right)\left( {x + 5} \right)}}} \right):\frac{{2x – 5}}{{x\left( {x + 5} \right)}} + \frac{x}{{5 – x}}\\
= \frac{{10x – 25}}{{x\left( {x – 5} \right)\left( {x + 5} \right)}}.\frac{{x\left( {x + 5} \right)}}{{2x – 5}} + \frac{x}{{5 – x}}\\
= \frac{5}{{x – 5}} – \frac{x}{{x – 5}}\\
= \frac{{5 – x}}{{x – 5}} = – 1
\end{array}\)
Đáp án:
Giải thích các bước giải:
$\color {orange } { A = ( \frac{x}{x ^ 2} – 25 – x – \frac{5}{x ^ 2} + 5x ) \div (2x – \frac{5}{x ^ 2} + 5x) + \frac{x}{5} – x \\\Leftrightarrow A = ( \frac{1}{x} – 25 – \frac{5}{x ^ 2 } + 4x) \div (7x + \frac{5}{x ^ 2}) + \frac{x}{5} – x \\\Leftrightarrow (7x + \frac{5}{x ^ 2})A = \frac{1}{x} – 25 – \frac{5}{x ^ 2} } $