Hoạt động 2 trang 30 Toán 8 Tập 1

Cho hai phân số <span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: 400; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: 0px; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: #000000; font-family: 'Open Sans', Arial, sans-serif; font-variant-ligatures: normal; font-variant-caps: normal; orphans: 2; widows: 2; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac></math>"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac><mo> </mo><mi>v</mi><mi>à</mi><mo> </mo><mfrac><mi>c</mi><mi>d</mi></mfrac></math> Nêu quy tắc để hai phân số bằng nhau. Lời giải: Quy tắc để hai phân số bằng nhau là: Hai phân số <span id="MathJax-Element-3-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac></math>"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac><mi>v</mi><mi>à</mi><mo> </mo><mfrac><mi>c</mi><mi>d</mi></mfrac></math><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi></mi></mfrac></math> được gọi là bằng nhau nếu a . d = b . c, viết là <span id="MathJax-Element-5-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac></math>"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac><mo>=</mo><mfrac><mi>c</mi><mi>d</mi></mfrac></math>

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