Solution 2.1:1g
From Förberedande kurs i matematik 1
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- | {{ | + | The expression in the exercise is of the form <math> (a-b)^2 </math>, where <math> a=y^2</math> and <math> b=3x^2 </math>. With the help of the squaring rule <math> (a-b)^2 =a^2 -2ab +b^2 </math>, we have |
- | < | + | |
- | {{ | + | {{Displayed math||<math>\begin{align} |
+ | (y^2-3x^3)^2 &= (y^2)^2 -2\cdot y^2\cdot 3x^3 +(3x^3)^2 \\[3pt] | ||
+ | &= y^{2\cdot 2} -6x^3y^2 +3^2x^{3\cdot 2}\\[3pt] | ||
+ | &= y^4 -6x^3y^2 +9x^6\\[3pt] | ||
+ | &= 9x^6 -6x^3y^2 +y^4\,\textrm{.} | ||
+ | \end{align}</math>}} |
Current revision
The expression in the exercise is of the form \displaystyle (a-b)^2 , where \displaystyle a=y^2 and \displaystyle b=3x^2 . With the help of the squaring rule \displaystyle (a-b)^2 =a^2 -2ab +b^2 , we have
\displaystyle \begin{align}
(y^2-3x^3)^2 &= (y^2)^2 -2\cdot y^2\cdot 3x^3 +(3x^3)^2 \\[3pt] &= y^{2\cdot 2} -6x^3y^2 +3^2x^{3\cdot 2}\\[3pt] &= y^4 -6x^3y^2 +9x^6\\[3pt] &= 9x^6 -6x^3y^2 +y^4\,\textrm{.} \end{align} |