Domain: {x element R : x>0} (all positive real numbers)
(assuming a function from reals to reals)
Solve for x:
(log(2 x^2+3 x))/(log(10)) = (log(6 x+2))/(log(10))
Subtract (log(6 x+2))/(log(10)) from both sides:
(log(2 x^2+3 x))/(log(10))-(log(6 x+2))/(log(10)) = 0
Bring (log(2 x^2+3 x))/(log(10))-(log(6 x+2))/(log(10)) together using the common denominator log(10):
-(log(6 x+2)-log(2 x^2+3 x))/(log(10)) = 0
Multiply both sides by -log(10):
log(6 x+2)-log(2 x^2+3 x) = 0
log(6 x+2)-log(2 x^2+3 x) = log(6 x+2)+log(1/(2 x^2+3 x)) = log((6 x+2)/(2 x^2+3 x)):
log((6 x+2)/(2 x^2+3 x)) = 0
Cancel logarithms by taking exp of both sides:
(6 x+2)/(2 x^2+3 x) = 1
Multiply both sides by 2 x^2+3 x:
6 x+2 = 2 x^2+3 x
Subtract 2 x^2+3 x from both sides:
-2 x^2+3 x+2 = 0
The left hand side factors into a product with three terms:
-(x-2) (2 x+1) = 0
Multiply both sides by -1:
(x-2) (2 x+1) = 0
Split into two equations:
x-2 = 0 or 2 x+1 = 0
Add 2 to both sides:
x = 2 or 2 x+1 = 0
Subtract 1 from both sides:
x = 2 or 2 x = -1
Divide both sides by 2:
Answer: | x = 2 or x = -1/2 (assuming a complex-valued logarithm)
Domain: {x element R : x>0} (all positive real numbers)
(assuming a function from reals to reals)
Solve for x:
(log(2 x^2+3 x))/(log(10)) = (log(6 x+2))/(log(10))
Subtract (log(6 x+2))/(log(10)) from both sides:
(log(2 x^2+3 x))/(log(10))-(log(6 x+2))/(log(10)) = 0
Bring (log(2 x^2+3 x))/(log(10))-(log(6 x+2))/(log(10)) together using the common denominator log(10):
-(log(6 x+2)-log(2 x^2+3 x))/(log(10)) = 0
Multiply both sides by -log(10):
log(6 x+2)-log(2 x^2+3 x) = 0
log(6 x+2)-log(2 x^2+3 x) = log(6 x+2)+log(1/(2 x^2+3 x)) = log((6 x+2)/(2 x^2+3 x)):
log((6 x+2)/(2 x^2+3 x)) = 0
Cancel logarithms by taking exp of both sides:
(6 x+2)/(2 x^2+3 x) = 1
Multiply both sides by 2 x^2+3 x:
6 x+2 = 2 x^2+3 x
Subtract 2 x^2+3 x from both sides:
-2 x^2+3 x+2 = 0
The left hand side factors into a product with three terms:
-(x-2) (2 x+1) = 0
Multiply both sides by -1:
(x-2) (2 x+1) = 0
Split into two equations:
x-2 = 0 or 2 x+1 = 0
Add 2 to both sides:
x = 2 or 2 x+1 = 0
Subtract 1 from both sides:
x = 2 or 2 x = -1
Divide both sides by 2:
Answer: | x = 2 or x = -1/2 (assuming a complex-valued logarithm)
log (2x^2 + 3x) = log (6x + 2)
Since the bases are the same, we can solve for the anti-logs
2x^2 + 3x = 6x + 2 rearrange as
2x^2 + 3x - 6x - 2 = 0 simplify
2x^2 - 3x - 2 = 0 factor
(2x + 1) (x - 2) = 0 set each factor to 0 and we get the possible solutions of x = -1/2 or x = 2
Reject x = -1/2 since it would result in taking the log of a negative number on both sides
Then.......x = 2 is the only (real) solution
The domain of the equation on the left would be (-inf, -3/2) U (0, inf)
The domain of the equation on the right would be (-1/3, inf)
Since we must choose the most restrictive interval, the domain for both functions is (0, inf)