Can anyone share the process please? ​

3x³ + x² + x + 1

= 3x³ - 3x² + 4x² - 4x + 5x - 5 + 6

= 3x²(x - 1) + 4x(x - 1) + 5(x - 1) + 6

= (x - 1)(3x² + 4x + 5) + 6

but 3x³ + x² + x + 1 = (x - 1).Q(x) + R

=> Q(x) = 3x² + 4x + 5

R = 6

(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