Algunos aspectos del desarrollo del pensamiento algebraico: el concepto de raíz y de variable en ecuaciones polinómicas de segundo grado. Un estudio de casos realizado con estudiantes uruguayos de ense？anza secundaria

we present research results in relation with equation producing given certain conditions, and understanding of the concept of variable in the context of equation solving, by secondary level uruguayan students. our results demonstrate some of the difficulties that students have with formulating examples of equations given their roots, the strategies that they use in order to determine if certain given numbers are roots of an equation, and the problem of understanding that a second degree equation with one unknown can have two different roots; aspects that illustrate some facets of the long process of the acquisition of the variable concept.