Question

If X varies directly as 2n+1, and n=4 when x=6, find n when x=18

Answer 1

x=2n+1 x=6 n=4
6=2 times 4 +1=9
6=9 and since 18 divided by 6=3, then n=9 times 3 which equals to 27

n=27

Answer 2

If X varies directly as 2n+1, and n=4 when x=6, find n when x=18

Explanation:

When X = 6, n = 4 in the formula x = 2n + 1, it would remain as: 6 = (2x4) + 1 = 9.

With a rule of 3, when 18 = n; 6 = 9; n = 18 x 9/6 = 27

n = 27