if (1+ax +bx^{2})(1-2x)^{18} be expressed in ascending powers of x such that coefficient of x^{3} and x^{4} are 0 then (a,b)is equal to :

a) (16,272/3) b) (4,44/3)

c)(1/16,88/3)

The given expression can be express by binomial theorem as follow

It is given that the coefficients of are zero. Therefore we have

Now, we will add the equation (1) and equation (2), we get

From equation (2), we have

Hence, the correct option is (*a *)

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