zondag 8 december 2019

Kwadraatafsplitsen

\( \begin{array}{l} \left\{ \begin{array}{l} L + W = 150 \\ L \cdot W = 4400 \\ \end{array} \right. \\ \left\{ \begin{array}{l} L + W = 150 \\ L = \frac{{4400}}{W} \\ \end{array} \right. \\ \left\{ \begin{array}{l} \frac{{4400}}{W} + W = 150 \\ L = \frac{{4400}}{W} \\ \end{array} \right. \\ \left\{ \begin{array}{l} 4400 + W^2 = 150W \\ L = \frac{{4400}}{W} \\ \end{array} \right. \\ \left\{ \begin{array}{l} W^2 - 150W + 4400 = 0 \\ L = \frac{{4400}}{W} \\ \end{array} \right. \\ W^2 - 150W + 4400 = 0 \\ (W - 75)^2 - 5625 + 4400 = 0 \\ (W - 75)^2 - 1225 = 0 \\ (W - 75)^2 = 1225 \\ W - 75 = \pm 35 \\ W = 40 \vee W = 110 \\ \end{array} \)