When x increases from a to a +2, y increases by a factor of 1/4

y=7* (0.5)^x

Step-by-step explanation:

We are given that when x increases from 'a' to 'a+2' then y must increase by a factor of 1/4=0.25.

i.e. when x=a and x'=a+2.

then y/y=0.25 where y' is the function after putting x' to the old function.

(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