Question

determine decimo segundo termo da PA
(1\4,7\12,...)

Answer 1

a) Calculo da razão da PA:

$\frac{7}{12}-\frac{1}{4}=\frac{7-3}{12}=\frac{4}{12}=\frac{1}{3}$

b) Calculo do 12o. termo:

$a_{12}=a_1+11R\\ \\ a_{12}=\frac{1}{4}+11*\frac{1}{3}\\ \\ a_{12}=\frac{1}{4}+\frac{11}{3}=\frac{3+44}{12}=\frac{47}{12}$