The expression is .

Compare the binomial expression with

Then .

First term  power is . \ \

Second term  power is .

So in binomial expression powers of x are in series of

So third term in binomial expansion is x² term.

So j = 8 − 3 + 1 = 6.

The formula for coefficient of in the expression of is .

The coefficient of in the expression of is .

The x² coefficient of the given expansion is 252.