A Solução das Quadráticas e Cúbicas na História

http://dx.doi.org/10.5902/2179460X14595For a long time the search to solve equations pushed the brilliant minds in the human History. Arithmetical, geometric and algebraic mechanisms ere developed bringing advance to the mathematics knowledge. A lot of these resources were "simplified" and nowadays they're handled in the classroom overruling among them the algebraic manipulation. This article, gotten from chapter 1 of Math Master dissertation in the PROFMAT Program from UFRPE and named A Geometrical Approach to the cubic Equations shows as from the history of algebra a geometrical manner, not usual anymore, to find the solution to second and third degree equations.Por muito tempo a busca para solucionar equações instigou brilhantes mentes da história humana. Mecanismos aritméticos, geométricos e algébricos foram desenvolvidos trazendo avanços ao conhecimento matemático. Muitos desses recursos foram “simplificados” e hoje são abordados nas salas de aula, prevalecendo, dentre eles, a manipulação algébrica. Este artigo, obtido do capítulo 1 da dissertação de mestrado em Matemática no Programa PROFMAT pela UFRPE e intitulado Uma abordagem Geométrica para as equações cúbicas, apresenta a partir da história da álgebra, uma maneira geométrica, já não usual, para encontrar a solução de equações de segundo e terceiro graus

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity

Núcleos de Ensino da Unesp: artigos 2008

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq