If f(x)=x-5, find x when f(x)=15

x = 20

Step-by-step explanation:

we are given the value of f(x), replace it in the first equation

15 = x - 5

solve for x by adding 5 on both sides

15 + 5 = x

20 = x or x = 20

(n^3 - n)

= n(n-1)(n+1)

since it is divisible by 3 and 2 ,because it is a multiple 3 consecutive number

if, n-1 is odd then n+1 is also odd, then it is a multiple of 9

but if, n-1 is even then n+1 is also even, then it is a multiple of 4

so, largest multiple = max(9*2, 4*3) = max(18, 12) = 18