Let I = \(\int\limits_4^{12} \)x(x - 4)\(\frac13\)dx
Put x – 4 = t3
⇒ dx = 3t2dt (Differentiating both sides)
When x = 4, t3 = 4 – 4 = 0 ⇒ t = 0
When x = 12, t3 = 12 – 4 = 8 ⇒ t = 2
So, the new limits are 0 and 2.
We can write x = t3 + 4
Substituting this in the original integral,