Solution 2.1:1f
From Förberedande kurs i matematik 1
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Revision as of 06:33, 21 August 2008
The squaring rule \displaystyle (a+b)^2 = a^2+2ab+b^2 with \displaystyle a=5 and \displaystyle b=4y gives
\displaystyle \qquad \begin{align} (5+4y)^2 &= 5^2+ 2\cdot 5 \cdot 4y +(4y)^2 \\ &= 25+10\cdot 4y + 4^2y^2\\ &= 25+40y+16y^4\\ &= 16y^2 +40y + 25 \end{align}
