Wednesday, July 2, 2014

Decide the number of solutions of the equation?2*25^x = 1+5^x

2*25^x =1+5^x


To solve this
equation, we put 5^x = y.


Then 25^x = (5^2)x = (5^x)^2 =
y^2.


So now we can rewrite the given equation
as:


2*y^2 =1+y


2y^2 -y -1 =
0


(2y+1)(y-1) = 0


2y+1 = 0 or
y-1 = 0.


y -1 = 0 gives: y = 1.
Or


5^x = 1 5^0


x =
0.


2y+1  = 0 gives: y = -1/2..
Or


5^x = -1/2. Thereis nor real solution. as for all real
x, 5^x > 0.


Therefore there is only one real
solution , that is , x = 0.

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