Question

Se a media aritmética entre n,n- 1,2n+1e4 é 10 determine o valor de n

Answer 1

$\dfrac{n+(n-1)+(2n+1)+4}{4}=10\\\\ \dfrac{n+(n-1)+(2n+1)+4}{ 4 }\cdot 4=10\cdot4\\\\ n+n+2n+4}=40\\\\ 4n+4 = 40\\\\ 4n+4-4=40-4\\\\ 4n = 36\\\\ n= \dfrac{36}{4} \quad \therefore \quad n = 9$