2. T_n=a.r^n-1

   The give series is 3,3,1, ..........,1/243

    a=3  r=1/3     Tn=1/243

     hence 1/243=3.(  1/3)^n-1

                   3^-6=(1/3)^(n-1)/2

             i.e.  -6= -(n-1)/2

                 12=n-1

                  n=13

 

 

give me the ratings dude.

If , are the eccentric angles of the extrimities of the focal chord of the ellipse

x²/a²+y²/b²=1, then find the eccentricity of the ellipse?

 

yust easy man. you must try to eleminate the parametric term.or use differentiation to solve it man.

like the common question

x=t²+t+1, and y=t²-t+1

x+y=2(t²+1), t²=(x+y-2)/2 --------(1)

x-y=2t, t=(x-y)/2 ,  t²=(x-y)²/4 -------(2)

hence, (x-y)²/4=(x+y-2)/2

 

give me the rating man for my work

 

 

 

ok da

maximum value of c cos(A-)+a cos(C+) is

a. a            b. b             c. c           d. a²+b²

The equation of the smallest circle the point of intersection of the line x+y=1 and the circle x²+y²=9 is

a. x²+y²+x+y-8=0

b. x²+y²-x-y-8=0

c. x²+y²-x+y-8=0

d. none of these.