Question

qual o 20° termo de uma pa (-2,3,8)

Answer 1

a20 = -2 + (20-1).5
a20 = 93

Answer 2

$\mathtt{R = A_2 - A_1} \\ \mathtt{R = 3 - (-2)} \\ \mathtt{R = 3 + 2} \\ \mathtt{R = 5}$

$\mathtt{A_n = A_1 + (n-1)~.~R } \\ \mathtt{A_{20} = -2+(20-1)~.~5} \\ \mathtt{A_{20} = -2+ 19~.~5} \\ \mathtt{A_{20} = -2 + 95 } \\ \mathtt{A_{20} = 93} \\ \\ \\ \boxed{\boxed{\mathtt{Resoista :A_{20}=93}}}$