Question

Numa PA a1+a2=3 e a4+a5=24, a razão da PA é?

Answer 1

$\Large\boxed{\begin{array}{l}\sf a_1+a_2=3\\\sf a_1+a_1+r=3\implies 2a_1+r=3\\\sf a_4+a_5=24\\\sf a_1+3r+a_1+4r=24\\\sf 2a_1+7r=24\\-\underline{\begin{cases}\sf 2a_1+7r=24\\\sf 2a_1+r=3\end{cases}}\\\sf 6r=21\\\sf r=\dfrac{21\div3}{6\div3}\\\\\sf r=\dfrac{7}{2}\checkmark\end{array}}$