Sunday, March 1, 2015

Verify if log equation have real root log(2x-5)=log(x^2+3)

To verify if the roots of the equation are real numbers,
we'll have to compute the roots. Before solving the equation, we'll impose the
constraints of existence of logarithms.


Since x^2+3 is
positive for any value of x, we'll set the only constraint for the given
equation:


2x -
5>0


2x>5


x>5/2


log
(2x-5) = log (x^2+3)


Since the bases are matching, we'll
use the one to one property:


2x - 5 = x^2 +
3


We'll move all terms to one
side:


x^2 + 3 - 2x + 5 =
0


We'll combine like
terms:


x^2 - 2x + 8 = 0


We'll
apply the quadratic formula:


x1 = [-b+sqrt(b^2 -
4ac)]/2a


x1 = [2+sqrt(4 -
32)]/2


Since sqrt (-28) is not a real value,
the equation has no real solutions.

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