Question

anyone who wants to answer my two questions of maths ch -arithmetic progressions..
..
-->15 points .
-->nice answer.

Answer 1

Hey there !!!!

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21)     n-2,4n-1,5n+2 are in AP   n=??

If a,b,c are in A.P

                b=(a+c)/2

Here a=n-2   b=4n-1   c=5n+2


             4n-1=(n-2+5n+2)/2

             2(4n-1)=6n

               8n-2=6n

               8n-6n=2

                 2n=2

                 n=1

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22)Sum of three numbers in AP=3    and  product=-35

Let the three numbers be   a-d,a,a+d

Sum :

                a-d+a+a+d=3

                   3a=3

                 a=1

Product:

  (a-d)(a)(a+d)=-35

Substituting a=1 

  (1-d)(1+d)=35

      1-d²=35

       d²=36

       d= +√36 or -√36

   d= +6 or -6

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Hope this helped you...............