Hướng dẫn giải Bài 24 (Trang 17 SGK Toán Đại số 8, Tập 2)

<p>Giải các phương trình:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>a</mi><mo>)</mo><mo> </mo><mo>(</mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>2</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>-</mo><mn>4</mn><mo>=</mo><mn>0</mn><mspace linebreak="newline"/><mi>b</mi><mo>)</mo><mo> </mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mi>x</mi><mo>=</mo><mo>-</mo><mn>2</mn><mi>x</mi><mo>+</mo><mn>2</mn><mspace linebreak="newline"/><mi>c</mi><mo>)</mo><mo> </mo><mn>4</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>4</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>=</mo><msup><mi>x</mi><mn>2</mn></msup><mspace linebreak="newline"/><mi>d</mi><mo>)</mo><mo> </mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>5</mn><mi>x</mi><mo>+</mo><mn>6</mn><mo>=</mo><mn>0</mn></math></p> <p><strong>Giải</strong></p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>a</mi><mo>)</mo><mo> </mo><mo>(</mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>2</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>-</mo><mn>4</mn><mo>=</mo><mn>0</mn><mo>⇔</mo><msup><mrow><mo>(</mo><mi>x</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow><mn>2</mn></msup><mo>-</mo><msup><mn>2</mn><mrow><mn>2</mn></mrow></msup><mo>=</mo><mn>0</mn><mspace linebreak="newline"/><mo>⇔</mo><mfenced open="[" close="]"><mrow><mo>(</mo><mi>x</mi><mo>-</mo><mn>1</mn><mo>)</mo><mo>+</mo><mn>2</mn></mrow></mfenced><mfenced open="[" close="]"><mrow><mo>(</mo><mi>x</mi><mo>-</mo><mn>1</mn><mo>)</mo><mo>-</mo><mn>2</mn></mrow></mfenced><mo>=</mo><mn>0</mn><mspace linebreak="newline"/><mo>⇔</mo><mo>(</mo><mi>x</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>(</mo><mi>x</mi><mo>-</mo><mn>3</mn><mo>)</mo><mo>=</mo><mn>0</mn><mo>⇒</mo><mi>S</mi><mo>=</mo><mfenced open="[" close="]"><mrow><mo>-</mo><mn>1</mn><mo>;</mo><mn>3</mn></mrow></mfenced><mspace linebreak="newline"/><mspace linebreak="newline"/><mi>b</mi><mo>)</mo><mo> </mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mi>x</mi><mo>=</mo><mo>-</mo><mn>2</mn><mi>x</mi><mo>+</mo><mn>2</mn><mo>⇔</mo><mi>x</mi><mo>(</mo><mi>x</mi><mo>-</mo><mn>1</mn><mo>)</mo><mo>-</mo><mn>2</mn><mo>(</mo><mi>x</mi><mo>-</mo><mn>1</mn><mo>)</mo><mo>=</mo><mn>0</mn><mspace linebreak="newline"/><mo>⇔</mo><mo>(</mo><mi>x</mi><mo>-</mo><mn>1</mn><mo>)</mo><mo>(</mo><mi>x</mi><mo>+</mo><mn>2</mn><mo>)</mo><mo>=</mo><mn>0</mn><mo>⇒</mo><mi>S</mi><mo>=</mo><mfenced open="[" close="]"><mrow><mo>-</mo><mn>2</mn><mo>;</mo><mn>1</mn></mrow></mfenced><mspace linebreak="newline"/><mspace linebreak="newline"/><mi>c</mi><mo>)</mo><mo> </mo><mn>4</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>4</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>=</mo><msup><mi>x</mi><mn>2</mn></msup><mo>⇔</mo><msup><mrow><mo>(</mo><mn>2</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mn>2</mn></msup><mo>-</mo><msup><mi>x</mi><mrow><mn>2</mn></mrow></msup><mo>=</mo><mn>0</mn><mspace linebreak="newline"/><mo>⇔</mo><mo>(</mo><mn>3</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>(</mo><mi>x</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>=</mo><mn>0</mn><mo>⇒</mo><mi>S</mi><mo>=</mo><mfenced open="{" close="}"><mrow><mo>-</mo><mn>1</mn><mo>;</mo><mo>-</mo><mfrac><mn>1</mn><mn>3</mn></mfrac></mrow></mfenced><mspace linebreak="newline"/><mspace linebreak="newline"/><mi>d</mi><mo>.</mo><mo> </mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>5</mn><mi>x</mi><mo>+</mo><mn>6</mn><mo>=</mo><mn>0</mn><mo>⇔</mo><mi>x</mi><mo>(</mo><mi>x</mi><mo>-</mo><mn>2</mn><mo>)</mo><mo>-</mo><mn>3</mn><mo>(</mo><mi>x</mi><mo>-</mo><mn>2</mn><mo>)</mo><mo>=</mo><mn>0</mn><mspace linebreak="newline"/><mo>⇔</mo><mo>(</mo><mi>x</mi><mo>-</mo><mn>2</mn><mo>)</mo><mo>(</mo><mi>x</mi><mo>-</mo><mn>3</mn><mo>)</mo><mo>=</mo><mn>0</mn><mo>⇒</mo><mi>S</mi><mo>=</mo><mfenced open="[" close="]"><mrow><mn>2</mn><mo>;</mo><mn>3</mn></mrow></mfenced></math></p>

Hướng dẫn Giải Bài 24 (Trang 17, SGK Toán 8, Tập 2, Phần Đại Số)

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Hướng dẫn giải Bài 23 (Trang 17 SGK Toán Đại số 8, Tập 2)

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