If `x_(1), x_(2), x_(3) .................x_(n)` are in H.P.then `x_(1)x_(2)+x_(2)x_(3)+.......+x_(n-1)x_(n)`=

If x_(1),x_(2),x_(3)...x_(n) are in H.P,then prove that x_(1)x_(2)+x_(2)x_(3)+xx x-3x_(4)+...+x_(n-1)x_(n)=(n-1)x_(1)x_(n)

If x_(1), x_(2),"……….",x_(n) are n non zero real numbers such that (x_(1)^(2) + x_(2)^(2) + "...."+x_(n-1)^(2))( x_(2)^(2) + x_(3)^(2) + x_(3)^(2) + "......" + x_(n)^(2))le ( x_(1) x_(2) + x_(2) x_(3)+"....."+x_(n-1)x_(n))^(2) , then x_(1) , x_(2) ,".....",x_(n) are in :

If x_(1),x_(2),x_(3),......x2_(n) are in A.P, then sum_(r=1)^(2n)(-1)^(r+1)x_(r)^(2) is equal to

If the S.D of x_(1),x_(2),x_(3),........x_(n) is 6, then the S.D of -x_(1),-x_(2),.......,-x_(n) is

Q.if x_(1),x_(2)......x_(n) are in H.P. then sum_(r=1)^(n)x_(r)x_(r+1) is equal to :(A)(n-1)x_(1)x_(n)(B)nx_(1)x_(n)(C)(n+1)x_(1)x_(n)(D)(n+2)x_(1)x_(n)

If x_(1),x_(2),x_(3),.......x_(n) are the roots of x^(n)+ax+b=0, then the value of (x_(1)-x_(2))(x_(1)-x_(3))(x_(1)-x_(4))......(x_(1)x_(n)) is equal to

If x_(1),x_(2),x_(3),"……" are in A.P., then the value of 1/(x_(1)x_(2))+1/(x_(2)x_(3))+1/(x_(3)x_(4))+"……"1/(x_(n-1)x_(n)) is :

If x_(1),x_(2),x_(3),x_(n) are the roots of x^(n)+ax+b=0 then the value of (x_(1)-x_(2))(x_(1)-x_(3))(x_(1)-x_(4))......(x_(1)-x_(n)) is equal to