Bài 2: Căn thức bậc hai và hằng đẳng thức <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msup><mi>A</mi><mn>2</mn></msup></msqrt><mo>=</mo><mfenced open="|" close="|"><mi>A</mi></mfenced></math>
Hướng dẫn giải Bài 8 (Trang 10 SGK Toán 9, Tập 1)
<p><strong>Bài 8 (Trang 10 SGK Toán 9, Tập 1):</strong></p>
<p>Rút gọn các biểu thức sau:</p>
<p>a) <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><msqrt><mo>(</mo><mn>2</mn><mo>-</mo><msqrt><mn>3</mn></msqrt></msqrt><mo>)</mo></mrow><mn>2</mn></msup></math></p>
<p>b) <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msup><mfenced><mrow><mn>3</mn><mo>-</mo><msqrt><mn>11</mn></msqrt></mrow></mfenced><mn>2</mn></msup></msqrt></math></p>
<p>c) <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><msqrt><mi mathvariant="normal">a</mi></msqrt><mo> </mo><mi>với</mi><mo> </mo><mi mathvariant="normal">a</mi><mo>≥</mo><mn>0</mn></math></p>
<p>d) <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn><msqrt><msup><mfenced><mrow><mi mathvariant="normal">a</mi><mo>-</mo><mn>2</mn></mrow></mfenced><mn>2</mn></msup></msqrt><mo> </mo><mi>với</mi><mo> </mo><mi mathvariant="normal">a</mi><mo> </mo><mo><</mo><mo> </mo><mn>2</mn></math></p>
<p> </p>
<p><strong><span style="text-decoration: underline;"><em>Hướng dẫn giải:</em></span></strong></p>
<p>a) <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msup><mfenced><mrow><mn>2</mn><mo>-</mo><msqrt><mn>3</mn></msqrt></mrow></mfenced><mn>2</mn></msup></msqrt><mo>=</mo><mo> </mo><mfenced open="|" close="|"><mrow><mn>2</mn><mo>-</mo><msqrt><mn>3</mn></msqrt></mrow></mfenced><mo> </mo><mo>=</mo><mo> </mo><mn>2</mn><mo>-</mo><msqrt><mn>3</mn></msqrt></math></p>
<p><math xmlns="http://www.w3.org/1998/Math/MathML"><mfenced><mrow><mn>2</mn><mo> </mo><mo>-</mo><mo> </mo><msqrt><mn>3</mn></msqrt><mo> </mo><mo>></mo><mo> </mo><mn>0</mn><mo> </mo><mi>do</mi><mo> </mo><mn>2</mn><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>4</mn></msqrt><mo> </mo><mo>></mo><mo> </mo><msqrt><mn>3</mn></msqrt></mrow></mfenced></math></p>
<p>b) <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msup><mfenced><mrow><mn>3</mn><mo>-</mo><msqrt><mn>11</mn></msqrt></mrow></mfenced><mn>2</mn></msup></msqrt><mo> </mo><mo>=</mo><mo> </mo><mfenced open="|" close="|"><mrow><mn>3</mn><mo>-</mo><msqrt><mn>11</mn></msqrt></mrow></mfenced><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>11</mn></msqrt><mo> </mo><mo>-</mo><mo> </mo><mn>3</mn></math></p>
<p>Vì (<math xmlns="http://www.w3.org/1998/Math/MathML"><mfenced><mrow><msqrt><mn>11</mn></msqrt><mo> </mo><mo>-</mo><mo> </mo><mn>3</mn><mo> </mo><mo>></mo><mo> </mo><mn>0</mn><mo> </mo><mi>d</mi><mi>o</mi><mo> </mo><mn>3</mn><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>9</mn><mo> </mo></msqrt><mo> </mo><mo><</mo><mo> </mo><msqrt><mn>11</mn></msqrt></mrow></mfenced></math></p>
<p>c) <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><msqrt><msup><mi>a</mi><mn>2</mn></msup></msqrt><mo> </mo><mo>=</mo><mo> </mo><mn>2</mn><mfenced open="|" close="|"><mi>a</mi></mfenced><mo> </mo><mo>=</mo><mo> </mo><mn>2</mn><mi>a</mi><mo> </mo><mi>v</mi><mi>ớ</mi><mi>i</mi><mo> </mo><mi>a</mi><mo> </mo><mo>≥</mo><mo> </mo><mn>0</mn></math></p>
<p>d) <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn><msqrt><msup><mfenced><mrow><mi>a</mi><mo>-</mo><mn>2</mn></mrow></mfenced><mn>2</mn></msup></msqrt><mo> </mo><mo>=</mo><mo> </mo><mn>3</mn><mfenced open="|" close="|"><mrow><mi>a</mi><mo>-</mo><mn>2</mn></mrow></mfenced><mo>=</mo><mo> </mo><mn>3</mn><mo>(</mo><mn>2</mn><mo>-</mo><mi>a</mi><mo>)</mo><mo> </mo><mo>(</mo><mi>V</mi><mi>ì</mi><mo> </mo><mi>v</mi><mi>ớ</mi><mi>i</mi><mo> </mo><mi>a</mi><mo> </mo><mo><</mo><mo> </mo><mn>2</mn><mo> </mo><mi>t</mi><mi>h</mi><mi>ì</mi><mo> </mo><mn>2</mn><mo> </mo><mo>-</mo><mo> </mo><mi>a</mi><mo> </mo><mo>></mo><mo> </mo><mn>0</mn><mo>)</mo></math></p>
Hướng dẫn Giải Bài 8 (trang 10, SGK Toán 9, Tập 1)
GV: 
GV colearn
GV colearn
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Hướng dẫn Giải Bài 8 (trang 10, SGK Toán 9, Tập 1)
GV: GV colearn
GV colearn