We'll impose the constraints of existence of the
logarithms:
x>0
9-2x>0
=> -2x>-9 => x < 9/2
The common
interval of admissible values is (0 ; 9/2).
We'll solve the
equation using the product rule of logarithms:
lg x*(9-2x)
= 1
We'll take
antilogarithm:
x*(9-2x) =
10
We'll remove the
brackets:
9x - 2x^2 = 10
We'll
move all terms to the left:
-2x^2 + 9x - 10 =
0
2x^2 - 9x + 10 = 0
We'll
apply quadratic formula:
x1 = [9+sqrt(81 -
80)]/4
x1 = (9+1)/4
x1 =
5/2
x2 = 8/4
x2 =
2
Since both x values belong to the interval
(0 ; 9/2), we'll accept them as solutions: {2 ;
5/2}.
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