Respuesta :
a² ? x² + y² ? b²d(x,y) = e-(x²+y²)dA = r·dr·d?dM = d(x,y)·dAx² + y² = r² (cambio)M = ?e-(x² + y²)·dA = ?e-r²·r·dr·d? =?/2 b
?d? · ?e-r²·r·dr =
0 a
?d? · ?e-r²·r·dr =
0 a