Question

determine quantos multipols de 9 há entre 100 e 1 000

Answer 1

a₁ = 108

an = 999

r = 9

n = ?

$\boxed{an=a1 + (n-1)r}$

999 = 108 + (n-1) * 9

999 = 108 + 9n - 9

999 = 99 + 9n

999 - 99 = 9n

900 = 9n

900/9 = n

100 = n   $\to\textbf{100 multiplos}$