Bài 3: Lôgarit
<span data-v-a7c68f28="">Hướng dẫn giải Hoạt động 5 (Trang 63 SGK Toán Giải Tích 12)</span>
<p><strong class="content_question">Đề b&agrave;i</strong></p> <p>Cho&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>b</mi><mn>1</mn></msub><mo>=</mo><msup><mn>2</mn><mn>3</mn></msup><mo>;</mo><mo>&#160;</mo><msub><mi>b</mi><mn>2</mn></msub><mo>=</mo><msup><mn>2</mn><mn>5</mn></msup></math></p> <p>T&iacute;nh <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>1</mn></msub><mo>+</mo><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>1</mn></msub><msub><mi>b</mi><mn>2</mn></msub></math>&nbsp;v&agrave; so s&aacute;nh c&aacute;c kết quả.</p> <div class="content_method_container"> <p class="content_method_header"><strong class="content_method">Phương ph&aacute;p giải - Xem chi tiết</strong></p> <div class="content_method_content"> <p>Sử dụng c&ocirc;ng thức <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>log</mi><mi>a</mi></msub><mfenced><msup><mi>a</mi><mi>n</mi></msup></mfenced><mo>=</mo><mi>n</mi></math>&nbsp;v&agrave;&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>log</mi><mi>a</mi></msub><mfenced><mrow><mi>b</mi><mi>c</mi></mrow></mfenced><mo>=</mo><msub><mi>log</mi><mi>a</mi></msub><mi>b</mi><mo>+</mo><msub><mi>log</mi><mi>a</mi></msub><mi>c</mi></math></p> </div> </div> <p><strong class="content_detail">Lời giải chi tiết</strong></p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>1</mn></msub><mo>+</mo><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>2</mn></msub><mo>=</mo><msub><mi>log</mi><mn>2</mn></msub><msup><mn>2</mn><mn>3</mn></msup><mo>+</mo><msub><mi>log</mi><mn>2</mn></msub><msup><mn>2</mn><mn>5</mn></msup><mo>=</mo><mn>3</mn><mo>+</mo><mn>5</mn><mo>=</mo><mn>8</mn><mspace linebreak="newline"/><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>1</mn></msub><msub><mi>b</mi><mn>2</mn></msub><mo>=</mo><msub><mi>log</mi><mn>2</mn></msub><mfenced><mrow><msup><mn>2</mn><mn>3</mn></msup><mo>.</mo><msup><mn>2</mn><mn>5</mn></msup></mrow></mfenced><mo>=</mo><mi>log</mi><mfenced><msup><mn>2</mn><mrow><mn>3</mn><mo>+</mo><mn>5</mn></mrow></msup></mfenced><mo>=</mo><msub><mi>log</mi><mn>2</mn></msub><msup><mn>2</mn><mn>8</mn></msup><mo>=</mo><mn>8</mn></math></p> <p>Vậy&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>1</mn></msub><mo>+</mo><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>2</mn></msub><mo>=</mo><msub><mi>log</mi><mn>2</mn></msub><msub><mi>b</mi><mn>1</mn></msub><msub><mi>b</mi><mn>2</mn></msub></math></p>
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