Respostas

2013-08-08T03:59:59-03:00
A razão da PA pode ser escrita

r = a2 - a1 = a3 - a2

a) (3+x, 5x, 2x+11)


5x - (3 + x) = 2x + 11 - 5x
5x - 3 - x = 2x + 11 - 5x
5x + 5x - 2x - x = 11 + 3
7x = 14
x = 14/7
x = 2

PA
(3 + x, 5x, 2x + 11)
PA(3 + 2, 5.2, 2.2 + 11)
PA(5, 10, 15)

b) (1 - x, x - 2, 2x - 1)
x - 2 - (1 - x) = 2x - 1 - (
x - 2)
x - 2 - 1 + x = 2x -1 - x + 2
x - 2x + x + x = -1 + 2 + 2 + 1
x = 4

PA(1 - x, x - 2, 2x - 1)
PA(1 - 4, 4 - 2, 2.4 - 1)
PA(-3, 2, 7)