If `(1+x-2x^(2))^(8)=a_(0)+a_(1)x+a_(2)x^(2)+…a_(16)x^(16)` then the sum a1+a3+a5+.......+a15 ​ ​ is equal to

If (1+2x+3x^(2))^(10)=a_(0)+a_(1)x+a_(2)x^(2)+a_(3)x^(3)+ . . .+a_(20)x^(20), then

If (1+x+x)^(2n)=a_(0)+a_(1)x+a_(2)x^(2)+a_(2n)x^(2n) , then a_(1)+a_(3)+a_(5)+……..+a_(2n-1) is equal to

If (1+x-2x^2)^8 = 1 + a_1x + a_2x^2 + ……+ a_16 x^16 , then a_1 +a_3 + a_5 + ……+a_15 = ?

If (1+x) ^(15) =a_(0) +a_(1) x +a_(2) x ^(2) +…+ a_(15) x ^(15), then the value of sum_(r=1) ^(15) r . (a_(r))/(a _(r-1)) is-

If (1+x+x^(2))^(n)=a_(0)+a_(1)x+a_(2)x^(2)+….+a_(2n)x^(2n) where a_(0) , a(1) , a(2) are unequal and in A.P., then (1)/(a_(n)) is equal to :

If (1 + x+ 2x^(2))^(20) = a_(0) + a_(1) x + a_(2) x^(2) + …+ a_(40) x^(40) . The value of a_(0) + a_(2) + a_(4) + …+ a_(38) is

( 1 + x + x^(2))^(n) = a_(0) + a_(1) x + a_(2) x^(2) + …+ a_(2n) x^(2n) , then a_(0) + a_(1) + a_(2) + a_(3) - a_(4) + … a_(2n) = .

If (1+x+2x^(2))^(20) = a_(0) + a_(1)x^(2) "……" + a_(40)x^(40) , then find the value of a_(0) + a_(1) + a_(2) + "……" + a_(38) .

If (1+x+x^(2))^(3n+1)=a_(0)+a_(1)x+a_(2)x^(2)+…a_(6n+2)x^(6n+2) , then find the value of sum_(r=0)^(2n)(a_(3r)-(a_(3r+1)+a_(3r+2))/2) is______.

(1 + x+x^2)^8 = a_0 + a_1x +…….+a_16 x^16 then a_1 - a_3 + a_5- a_7 + ……..-a_15=