deletions | additions       diff --git a/introduction.tex b/introduction.tex  index 14881e5..112d34b 100644  --- a/introduction.tex  +++ b/introduction.tex 
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[ - A_{m} k_x^2 cos ( k_x x) - B_{m} k_x^2 sin ( k_x x) ]  [ C_{n} cos ( k_y y) + D_{n} sin ( k_y y) ]  \end{equation}  Calculando a primeira derivada de $h(x,y,z)$ em rela\c{c}\~ao a $y$ temos:   \begin{equation}   \frac{\partial h(x,y,z) }{\partial y} =   \sum^{\infty}_{n=0} \sum^{\infty}_{m=0} exp \{ - (k_x^2 +k_y^2)^{1/2} z \}   [ A_{m} cos ( k_x x) + B_{m} sin ( k_x x) ]   [ - C_{n} k_y sin ( k_y y) + D_{n} k_y cos ( k_y y) ]   \end{equation}