Tuesday, May 21, 2013

If (x-2) , 7 , (2x+1) are terms of an A.P , find x.

Given that:


(x-2) , 7 ,
(2x+1) are terms of an arithmetical progression.


Then, we
will assume that the common difference is r .


Then we know
that:


7 = (x-2) + r


==>
7 - r = x-2


==> x = 9 - r
................(1)


Also, we know
that:


2x+1 = 7 + r


==>
2x = 6 + r ..................(2)


Now we will add (1) and
(2).


==> 3x =
15


==> x = 15/3 = 5


To
check:


5 -2 = 3


2x +1 = 2(5) +
1 = 11


==> 3, 7, 11  are terms of an A.P where the
common difference is r = 4


==> x =
5

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