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i need help with a math question but it is for a send in assingment so if at all possible could you make a similar equation to the one i give so it isn't cheating?

solve for x algebraically

2log2(x-6) - log2x = 3

 Jan 4, 2017
 #1
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2 log(x - 6) - log(x) = log((x - 6)^2) + log(1/x) = log((x - 6)^2/x):
log((x - 6)^2/x) = 3 log(2)

3 log(2) = log(2^3) = log(8):
log((x - 6)^2/x) = log(8)

Cancel logarithms by taking exp of both sides:
(x - 6)^2/x = 8

Multiply both sides by x:
(x - 6)^2 = 8 x

Subtract 8 x from both sides:
(x - 6)^2 - 8 x = 0

Expand out terms of the left hand side:
x^2 - 20 x + 36 = 0

The left hand side factors into a product with two terms:
(x - 18) (x - 2) = 0

Split into two equations:
x - 18 = 0 or x - 2 = 0

Add 18 to both sides:
x = 18 or x - 2 = 0

Add 2 to both sides:
x = 18 or x = 2

(2 log(x - 6))/(log(2)) - (log(x))/(log(2)) ⇒ (2 log(2 - 6))/(log(2)) - (log(2))/(log(2)) = ((0 + 2 i) π + 3 log(2))/(log(2)) ≈ 3. + 9.06472 i:
So this solution is incorrect

(2 log(x - 6))/(log(2)) - (log(x))/(log(2)) ⇒ (2 log(18 - 6))/(log(2)) - (log(18))/(log(2)) = 3:
So this solution is correct

The solution is:
Answer: |x = 18

 Jan 4, 2017
 #2
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Example:

2log2(x+1)log2x=2log2(x+1)2log2x=2log2((x+1)2x)=2(x+1)2x=4x2+2x+1=4xx23x+1=0x=(3)±(3)2(4)(1)(1)2(1)=3±52x=3+52 or 352(rejected)x=3+52

Try to do your own question now!!

 Jan 5, 2017

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