Question

calcule quantos termos tem a P.A. (13,18,23,...,303)

Answer 1

$r=a_{2}-a_{1}=18-13=5$

$n=\dfrac{a_{n}-a_{1}}{r} +1$

$n=\dfrac{303-13}{5}+1$

$n=\dfrac{290}{5}+1$

$n=58+1$

$\boxed{\boxed{\mathsf{n=59}}}$