Question

determine o 18 termo da p.a (-6,-2,...)

Answer 1

a1 = -6
a2 = - 2
r = -2 - ( - 6) = -2 + 6 = 4 ***
n = 18
a1 + 17r = -6 + 17( 4) = -6 + 68 = 62 ***

Answer 2

$r=-2-(-6)=4\\\\a_{18}=a_2+16r\\\\a_{18}=-2+16(4)\\\\a_{18}=-2+64\\\\a_{18}=62$