Solution 3.1:4a
From Förberedande kurs i matematik 1
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| - | {{  | + | The decimal number   | 
| - | <  | + | <math>0.\text{16 }</math>  | 
| - | {{  | + | can also be written as   | 
| + | <math>\text{16}\centerdot \text{1}0^{-\text{2}}\text{ }</math>  | ||
| + | and then it is easier to see that, since   | ||
| + | <math>\text{16}=\text{4}\centerdot \text{4}=\text{4}^{\text{2}}\text{ }</math>  | ||
| + | and   | ||
| + | <math>10^{-2}=\left( 10^{-1} \right)^{2}=0.1^{2}</math>  | ||
| + | |||
| + | |||
| + | |||
| + | <math>\begin{align}  | ||
| + | & \sqrt{0.16}=\sqrt{16\centerdot 10^{-2}}=\sqrt{16}\centerdot \sqrt{10^{-2}}=\sqrt{4^{2}}\centerdot \sqrt{0.1^{2}} \\   | ||
| + | & =4\centerdot 0.1=0.4 \\   | ||
| + | \end{align}</math>  | ||
| + | |||
| + | |||
| + | Another alternative is, of course, to see directly  that   | ||
| + | <math>0.16=0.4\centerdot 0.4=0.4^{2}</math>, and then that   | ||
| + | <math>\sqrt{0.16}=\sqrt{0.4^{2}}=0.4</math>  | ||
Revision as of 13:50, 22 September 2008
The decimal number \displaystyle 0.\text{16 } can also be written as \displaystyle \text{16}\centerdot \text{1}0^{-\text{2}}\text{ } and then it is easier to see that, since \displaystyle \text{16}=\text{4}\centerdot \text{4}=\text{4}^{\text{2}}\text{ } and \displaystyle 10^{-2}=\left( 10^{-1} \right)^{2}=0.1^{2}
\displaystyle \begin{align} & \sqrt{0.16}=\sqrt{16\centerdot 10^{-2}}=\sqrt{16}\centerdot \sqrt{10^{-2}}=\sqrt{4^{2}}\centerdot \sqrt{0.1^{2}} \\ & =4\centerdot 0.1=0.4 \\ \end{align}
Another alternative is, of course, to see directly  that 
\displaystyle 0.16=0.4\centerdot 0.4=0.4^{2}, and then that 
\displaystyle \sqrt{0.16}=\sqrt{0.4^{2}}=0.4
