Question

Determine o vigésimo termo da PA (1/4,7/2,...)

Answer 1

Olá.

• $a_{1} = \frac{1}{4}$
• $r = \frac{7}{2} - \frac{1}{4} = \frac{14}{4} - \frac{1}{4} = \frac{13}{4}$

Termo geral da P.A.

$a_{n} = a_{1} + (n - 1) \times r \\ a_{20} = \frac{1}{4} + 19 \times \frac{13}{4} \\ a_{20} = \frac{1}{4} + \frac{247}{4} \\ a_{20} = \frac{248}{4} \\ a_{20} = 62$

Bons estudos.