If `a_(n)` is a geometric sequence with `a_(1)=2` and `a_(5)=18,` then the value of `a_(1)+a_(3)+a_(5)+a_(7)` is equal to

If a_(n) = 3-4n , then what is a_(1)+a_(2)+a_(3)+…+a_(n) equal to ?

If a_(1), a_(2), a_(3), ……. , a_(n) are in A.P. and a_(1) = 0 , then the value of (a_(3)/a_(2) + a_(4)/a_(3) + .... + a_(n)/a_(n - 1)) - a_(2)(1/a_(2) + 1/a_(3) + .... + 1/a_(n - 2)) is equal to

Consider an A.P*a_(1),a_(2),a_(3),.... such that a_(3)+a_(5)+a_(8)=11 and a_(4)+a_(2)=-2 then the value of a_(1)+a_(6)+a_(7) is....

If a_(1),a_(2),...a_(n) are in H.P then the expression a_(1)a_(2)+a_(2)a_(3)+...+a_(n-1)a_(n) is equal to

If the sequence (a_(n)) is in GP, such that a_(4)//a_(6)=1//4 and a_(2)+a_(5)=216, then a_(1) is equal to

If the sequence (a_(n)) is in GP, such that a_(4)//a_(6)=1//4 and a_(2)+a_(5)=216, then a_(1) is equal to

If a_(1) , a_(2), a_(3) , cdots ,a_(n) are in A.P. with a_(1) =3, a_(n) =39 and a_(1) +a_(2) + cdots +a_(n) =210 then the value of n is equal to

If a_(1), a_(2) , ……. A_(n) are in H.P., then the expression a_(1)a_(2) + a_(2)a_(3) + ….. + a_(n - 1)a_(n) is equal to