If the coefficient of `x^(3)` and `x^(4)` in the expansion of `(1+ax+bx^(2)) (1-2x)^(18)` in power of x are both zero, then `(a,b)` is equal to

If the coefficients of x^3 and x^4 in the expansion of (1""+a x+b x^2)""(1-2x)^(18) in powers of x are both zero, then (a, b) is equal to (1) (16 ,(251)/3) (3) (14 ,(251)/3) (2) (14 ,(272)/3) (4) (16 ,(272)/3)

If the coefficient x^(2) and x^(3) in the expansion of (1 + 8x + bx^(2))(1 - 3x)^(9) in the power of x are equal , then b is :

The ratio of coefficients x^(3) and x^(4) in the expansion of (1+x)^(12) is

The coefficient of x^(4) in the expansion of (1+x+x^(2))^(6) is

the coefficient of x^(r) in the expansion of (1 - 4x )^(-1//2) , is

The coefficient of x^(r) in the expansion of (1-ax-x^(2))/(e^(x)) is

The coefficient of x^4 in the expansion of (1+x-2x^2)^7 is

The coefficient of x^4 in the expansion of (1+x-2x^2)^7 is :

The coefficient of x^(n) in the expansion of ((1+x)^(2))/((1 - x)^(3)) , is

The coefficient of x^(n) in the expansion of (a+bx+cx^(2))/(e^(x)) is