Para representar $\mathbf{\frac{\textcolor{#ef4444}{1}}{\textcolor{#3b82f6}{3}}} + \mathbf{\frac{\textcolor{#ef4444}{1}}{\textcolor{#3b82f6}{4}}}$ na régua, é preciso medir as duas frações nos pedaços em que ela está partida: 12 avos. O 12 é o denominador comum, pois está na tabuada do 3 e na do 4.

Um terço da régua são 4 partes:

$\mathbf{\dfrac{\textcolor{#ef4444}{1}}{\textcolor{#3b82f6}{3}}}$

= $\mathbf{\dfrac{\textcolor{#ef4444}{1} \times 4}{\textcolor{#3b82f6}{3} \times 4}}$

= $\mathbf{\dfrac{\textcolor{#ef4444}{4}}{\textcolor{#3b82f6}{12}}}$

Um quarto da régua são 3 partes:

$\mathbf{\dfrac{\textcolor{#ef4444}{1}}{\textcolor{#3b82f6}{4}}}$

= $\mathbf{\dfrac{\textcolor{#ef4444}{1} \times 3}{\textcolor{#3b82f6}{4} \times 3}}$

= $\mathbf{\dfrac{\textcolor{#ef4444}{3}}{\textcolor{#3b82f6}{12}}}$

Juntando as partes de cima, no mesmo tamanho:

$\mathbf{\dfrac{\textcolor{#ef4444}{4}}{\textcolor{#3b82f6}{12}} + \dfrac{\textcolor{#ef4444}{3}}{\textcolor{#3b82f6}{12}}}$

= $\mathbf{\dfrac{\textcolor{#ef4444}{7}}{\textcolor{#3b82f6}{12}}}$

A soma vale $\mathbf{\frac{\textcolor{#ef4444}{7}}{\textcolor{#3b82f6}{12}}}$ da régua, ou seja, 7 das 12 partes. Como as partes são todas iguais, tanto faz quais sete pintar.

Resposta correta: pintar quaisquer 7 das 12 partes da régua.

Questão Q14846