Question

qual o numero de termo da pa (100,98,96,...,22)

Answer 1

an= a1+(n-1).r

22= 100+(n-1).(-2)

22= 100-2n+2

22= 102-2n

22-102= -2n

-80= -2n(×-1)

2n= 80

n=80/2

n=40