Question

Determine o 20° termo da P.A (5,11,17,23)

Answer 1

$P.A (5,11,17,23)\\\\ a_{1} =5\\ r=6\\n=20\\a_{n} = a_{20} =?\\\\\\ a_{n} = a_{1} +(n-1)*r\\\\\\ a_{20} =5 +(20-1)*6\to\\\\ a_{20} =5 +19*6\to \\\\a_{20} =5 +114\to\\\\ a_{20} =119$