Bài 5: Những Hằng Đẳng Thức Đáng Nhớ (Tiếp)
Hướng dẫn giải Bài 36 (Trang 17 SGK Toán Đại số 8, Tập 1)
<div class="i-head"> <p class="i-title">T&iacute;nh gi&aacute; trị của biểu thức:</p> <p class="i-title"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>a</mi><mo>)</mo><mo>&#160;</mo><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>4</mn><mi>x</mi><mo>+</mo><mn>4</mn><mo>&#160;</mo><mi>t</mi><mi>&#7841;</mi><mi>i</mi><mo>&#160;</mo><mi>x</mi><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>98</mn><mo>;</mo></math></p> <p class="i-title"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>b</mi><mo>)</mo><msup><mi>x</mi><mn>3</mn></msup><mo>+</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>3</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>&#160;</mo><mi>t</mi><mi>&#7841;</mi><mi>i</mi><mo>&#160;</mo><mi>x</mi><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>99</mn><mo>;</mo></math></p> <p class="i-title"><strong>Giải:</strong></p> <p class="i-title"><strong><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>a</mi><mo>)</mo><mo>&#160;</mo><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>4</mn><mi>x</mi><mo>+</mo><mn>4</mn><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><msup><mi>x</mi><mn>2</mn></msup><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mo>.</mo><mo>&#160;</mo><mi>x</mi><mo>&#160;</mo><mo>.</mo><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><msup><mn>2</mn><mn>2</mn></msup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><msup><mrow><mo>(</mo><mi>x</mi><mo>+</mo><mo>&#160;</mo><mn>2</mn><mo>)</mo></mrow><mn>2</mn></msup><mo>&#160;</mo><mspace linebreak="newline"/><mi>V</mi><mi>&#7899;</mi><mi>i</mi><mo>&#160;</mo><mi>x</mi><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>98</mn><mo>:</mo><mo>&#160;</mo><msup><mrow><mo>(</mo><mn>98</mn><mo>+</mo><mo>&#160;</mo><mn>2</mn><mo>)</mo></mrow><mn>2</mn></msup><mo>&#160;</mo><mo>=</mo><msup><mn>100</mn><mn>2</mn></msup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>10000</mn></math></strong></p> <p class="i-title"><strong><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>b</mi><mo>)</mo><mo>&#160;</mo><msup><mi>x</mi><mn>3</mn></msup><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><mi>x</mi><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><msup><mi>x</mi><mn>3</mn></msup><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><mo>&#160;</mo><mo>.</mo><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mo>.</mo><mo>&#160;</mo><msup><mi>x</mi><mn>2</mn></msup><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><mo>&#160;</mo><mo>.</mo><mo>&#160;</mo><mi>x</mi><mo>&#160;</mo><mo>.</mo><msup><mn>1</mn><mn>2</mn></msup><mo>+</mo><mo>&#160;</mo><msup><mn>1</mn><mn>3</mn></msup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><msup><mrow><mo>(</mo><mi>x</mi><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>1</mn><mo>)</mo></mrow><mn>3</mn></msup><mo>&#160;</mo><mspace linebreak="newline"/><mi>V</mi><mi>&#7899;</mi><mi>i</mi><mo>&#160;</mo><mi>x</mi><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>99</mn><mo>:</mo><mo>&#160;</mo><msup><mrow><mo>(</mo><mn>99</mn><mo>+</mo><mo>&#160;</mo><mn>1</mn><mo>)</mo></mrow><mn>3</mn></msup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><msup><mn>100</mn><mn>3</mn></msup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>1000000</mn></math></strong></p> </div>
Hướng dẫn Giải Bài 36 (Trang 17, SGK Toán 8, Tập 1)
GV: GV colearn
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Hướng dẫn Giải Bài 36 (Trang 17, SGK Toán 8, Tập 1)
GV: GV colearn