SOLUTION: These questions confuse me a bit and this site has helped me before. Thank you, please show me how to solve these problems (for x) . 16) log(x+4)-log6=1 18) log(x-1)^2=log(-5x-1)

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: These questions confuse me a bit and this site has helped me before. Thank you, please show me how to solve these problems (for x) . 16) log(x+4)-log6=1 18) log(x-1)^2=log(-5x-1)      Log On


   

Question 748655: These questions confuse me a bit and this site has helped me before. Thank you, please show me how to solve these problems (for x) .
16) log(x+4)-log6=1
18) log(x-1)^2=log(-5x-1)
please help. thank you again so much.
Found 2 solutions by stanbon, MathTherapy:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
log(x+4)-log6=1
log[(x+4)/6] = 1
(x+4)/6 = 10^1
x+4 = 60
x = 56
----------------------------
18) log(x-1)^2=log(-5x-1)
(x-1)^2 = -5x-1
x^2 -2x + 1 = -5x -1
-----
x^2 +3x = 0
x(x+3) = 0
x = 0 or x = -3
------------------
Cheers,
Stan H.

Answer by MathTherapy(10555) About Me  (Show Source):
You can put this solution on YOUR website!

please show me how to solve these problems (for x) .
16) log(x+4)-log6=1
18) log(x-1)^2=log(-5x-1)
please help. thank you again so much.


16) log(x+4)-log6=1

log%28%28x+%2B+4%29%29+-+log%286%29+=+1

log%28%28x+%2B+4%29%2F6%29+=+1

%28x+%2B+4%29%2F6+=+10%5E1

%28x+%2B+4%29%2F6+=+10

x + 4 = 60 ------- Cross-multiplying

x = 60 - 4, or highlight_green%28x+=+56%29


18) log(x-1)^2=log(-5x-1)

log%28%28x+-+1%29%29%5E2+=+log%28%28-+5x+-+1%29%29

%28x+-+1%29%5E2+=+-+5x+-+1

x%5E2+-+2x+%2B+1+=+-+5x+-+1

x%5E2+-+2x+%2B+5x+%2B+1+%2B+1+=+0

x%5E2+%2B+3x+%2B+2+=+0

(x + 1)(x + 2) = 0

highlight_green%28x+=+-+1%29, or highlight_green%28x+=+-+2%29

You can do the check on both!!

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