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If c,d are roots of X^2-10ax-11b=0 and a,b are roots of x^2-10ax-11b=0 and a,b are root of x^2-10cx-11d=0 , then value of a+b+c+d is

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Solution:      c+d=10a      .........(1)  and a+b=10c   ...........(2)

             Subtracting (1) from (2) We get

             (a-c)+(b-d)=10(c-a)

          Rightarrow       b-d=11(c-a)       ...........(3)

           As c is a root of x^2-10ax-11b=0

         We get  

                     c^2-10ac-11b=0      ...........(4)

                   a^2-10ac-11d=0       ..............(5)

          Subtracting (5) from(4)  ,we get 

    Rightarrow        c^2-a^2=11(b-d)

   Rightarrow      (c-a)(c+a)=(11)(11)(c-a)

   Rightarrow     (c+a)=121      

  	herefore         a+b+c+d=10(a+c)=10(121)=1210  

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Deependra Verma

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