Question

caucule a soma dos 20 primeiros termos da PA (0,15;0,40;0,65;0,90;...)

Answer 1

a1=0,15
r=0,40-0,15=0,25

a20=a1+(20-1).0,25
a20=0,15+19.0,25
a20=0,15+4,75
a20=4,9

S20= (a1+a20).20/2
S20=(0,15+4,9).20/2
S20=5,05.20/2
S20=101/2
S20=50,5