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# Logs help watch

1. 5. Solve the equation
2logx=log4 + log (2x+5)
2. Can you combine 2logx - log(2x+5) using the log rules?
3. (Original post by vc94)
Can you combine 2logx - log(2x+5) using the log rules?
which log rule do i use for that?
4. (Original post by princess271)
5. Solve the equation
2logx=log4 + log (2x+5)
What I did...

I re-wrote the expression....

logx^2=log4+log(2x+5)

I then used two of the log rules to do this...

10^(logx^2)=10^log4(2x+5)

You then get a quadratic equation to solve...
x^2=4(2x+5)
x^2=8x+20

Solution

X=10
x=-2

I hope this doesn't confuse you
5. (Original post by JunePlum)
What I did...

I re-wrote the expression....

logx^2=log4+log(2x+5)

I then used two of the log rules to do this...

10^(logx^2)=10^log4(2x+5)

You then get a quadratic equation to solve...
x^2=4(2x+5)
x^2=8x+20

Solution

X=10
x=-2

I hope this doesn't confuse you
thank you
^ is that a squared sign?
6. (Original post by princess271)
thank you
^ is that a squared sign?
Yes
x^2 means x 'squared'
7. (Original post by JunePlum)
Yes
x^2 means x 'squared'
ok thanks

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