If `cotA+cotB+cotC``=``k(1/x^2+1/y^2+1/z^2)` then the value of `k` is
`(A)` `R^2`
`(B)` `2R`
`(C)` `/_\`
``(D) a^2+b^2+c^2``

If 1/(1+2x+x^2)= 1+a_1x+a_2x^2+….. then the value of a_r is (A) 2 (B) r+1 (C) r (D) 2r

If x^2 + 5x - 2 k , is exactly divisible by (x-1), then the value of K is (A) 1 (B) 2 (C ) 3 (D) 4

If the lines (x-1)/2=(y+1)/3=(z-1)/4 and (x-3)/1=(y-k)/2=z/1 intersect then the value of k is (A) 2/9 (B) 9/2 (C) 0 (D) -1

If the lines (x-1)/2=(y+1)/3=(z-1)/4 and (x-3)/1=(y-k)/2=z/1 intersect then the value of k is (A) 3/2 (B) 9/2 (C) -2/9 (D) -3/2

The line (x-4)/1=(y-2)/1=(z-k)/2 lies exactly on the plane 2x-4y+z=7 then the value of k is (A) 7 (B) -7 (C) 1 (D) none of these

If x^(140)+2x^(151)+k is divisible by x+1, then the value of k is 1(b)-3(c)2(d)-2

In A B C , if b^2+c^2=2a^2, then value of (cotA)/(cotB+cotC) is 1/2 (b) 3/2 (c) 5/2 (d) 5/2

If A and B be two complex numbers such that |1-A'B|^(2)-|A-B|^(2)=K(1-|A|^(2))(1-|B|^(2)) then the value of k is (A)1(B)2(C)(1)/(2)(D)(1)/(3)

If a_1,a_2,a_3 are in G.P. having common ratio r such that sum_(k=1)^n a_(2k-1)= sum_(k=1)^na_(2k+2)!=0 then number of possible value of r is (A) 1 (B) 2 (C) 3 (D) none of these

In a Delta ABC , if b + c = 3a, then the value of cotB/2cotC/2, is