Hướng dẫn Giải Bài 56 (trang 30, SGK Toán 9, Tập 1)

Hướng dẫn giải Bài 56 (Trang 30 SGK Toán 9, Tập 1)

Bài 56 (Trang 30 SGK Toán 9, Tập 1): Sắp xếp theo thứ tự tăng dần: <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">a</mi><mo>)</mo><mo> </mo><mn>3</mn><msqrt><mn>5</mn></msqrt><mo>,</mo><mo> </mo><mo> </mo><mn>2</mn><msqrt><mn>6</mn></msqrt><mo>,</mo><mo> </mo><mo> </mo><mo> </mo><msqrt><mn>29</mn></msqrt><mo>,</mo><mo> </mo><mo> </mo><mn>4</mn><msqrt><mn>2</mn></msqrt><mo>;</mo></math> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">b</mi><mo>)</mo><mo> </mo><mn>6</mn><msqrt><mn>2</mn></msqrt><mo>,</mo><mo> </mo><msqrt><mn>38</mn></msqrt><mo>,</mo><mo> </mo><mo> </mo><mn>3</mn><msqrt><mn>7</mn></msqrt><mo>,</mo><mo> </mo><mn>2</mn><msqrt><mn>14</mn></msqrt></math>   Hướng dẫn giải: a) <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn><msqrt><mn>5</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><msup><mn>3</mn><mn>2</mn></msup><mo>.</mo><mn>5</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>9</mn><mo>.</mo><mn>5</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>45</mn></msqrt><mo>;</mo></math>    <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><msqrt><mn>6</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><msup><mn>2</mn><mn>2</mn></msup><mo>.</mo><mn>6</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>4</mn><mo>.</mo><mn>6</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>24</mn></msqrt><mo>;</mo></math>    <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>4</mn><msqrt><mn>2</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><msup><mn>4</mn><mn>2</mn></msup><mo>.</mo><mn>2</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>16</mn><mo>.</mo><mn>2</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>32</mn></msqrt><mo>;</mo></math> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>Vì</mi><mo> </mo><msqrt><mn>45</mn></msqrt><mo> </mo><mo>></mo><mo> </mo><msqrt><mn>32</mn></msqrt><mo> </mo><mo>></mo><mo> </mo><msqrt><mn>29</mn></msqrt><mo> </mo><mo>></mo><mo> </mo><msqrt><mn>24</mn></msqrt><mo> </mo><mi>nên</mi><mo> </mo><mn>2</mn><msqrt><mn>6</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><msqrt><mn>29</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><mn>4</mn><msqrt><mn>2</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><mn>3</mn><msqrt><mn>5</mn></msqrt><mo>.</mo></math> b) <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>6</mn><msqrt><mn>2</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><msup><mn>6</mn><mn>2</mn></msup><mo>.</mo><mn>2</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>36</mn><mo>.</mo><mn>2</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>72</mn></msqrt><mo>;</mo></math>    <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn><msqrt><mn>7</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><msup><mn>3</mn><mn>2</mn></msup><mo>.</mo><mn>7</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>9</mn><mo>.</mo><mn>7</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>63</mn></msqrt><mo>;</mo></math>    <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><msqrt><mn>14</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><msup><mn>2</mn><mn>2</mn></msup><mo>.</mo><mn>14</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>4</mn><mo>.</mo><mn>14</mn></msqrt><mo> </mo><mo>=</mo><mo> </mo><msqrt><mn>56</mn></msqrt><mo>;</mo></math> Vì <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>V</mi><mi>ì</mi><mo> </mo><msqrt><mn>38</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><msqrt><mn>56</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><msqrt><mn>63</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><msqrt><mn>72</mn></msqrt></math> nên <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mn>38</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><mn>2</mn><msqrt><mn>14</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><mn>3</mn><msqrt><mn>7</mn></msqrt><mo> </mo><mo><</mo><mo> </mo><mn>6</mn><msqrt><mn>2</mn></msqrt></math> Ta có thể sắp xếp theo thứ tự tăng dần như sau: <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mn>38</mn></msqrt><mo>,</mo><mo> </mo><mn>2</mn><msqrt><mn>14</mn></msqrt><mo>,</mo><mo> </mo><mn>3</mn><msqrt><mn>7</mn></msqrt><mo>,</mo><mo> </mo><mn>6</mn><msqrt><mn>2</mn></msqrt></math>.