Cuidado
Autor: MATEMÁTICA DA INFORMAÇÃO | Publicado: 2015-02-10T10:37:00-08:00

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Cuidado

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Um
sujeito comprou um arco e uma flecha por 11 reais. O arco custou 10 reais a
mais que a flecha. Pergunta: Quanto custou a flecha?

Cuidado, se apressadamente você
respondeu 1 real, está errado, já que se a flecha custou 1+10 = 11, portanto os
dois custaram 12 reais. Vamos pensar assim: Seja a o preço do arco e f o
da flecha. A frase “comprou um arco e uma flecha por 11 reais” matematiza-se da
forma&nbsp;&nbsp;&nbsp; &nbsp;a+f = 11 ; já “o arco custou 10
reais a mais que a flecha, escreve-se: a=f + 10” 

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Assim.,
a partir destas equações encontramos f = 0,50.

Fonte: Revista Cálculo novembro
2014