SOLUTION: Solve for x , show work please. Can someone check my answers please. 1). log4 (3x+4)^5=15 2). log (x^2-9)=log (5x+5) Here is a screenshot of them just incase. Link to sc

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: Solve for x , show work please. Can someone check my answers please. 1). log4 (3x+4)^5=15 2). log (x^2-9)=log (5x+5) Here is a screenshot of them just incase. Link to sc      Log On


   



Question 1020039: Solve for x , show work please. Can someone check my answers please.
1). log4 (3x+4)^5=15
2). log (x^2-9)=log (5x+5)
Here is a screenshot of them just incase. Link to screenshot : http://prntscr.com/a42nsg
my answer for #1 was no solution and my answer for #2 was x=7. Thanks !

Found 2 solutions by Cromlix, MathTherapy:
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,
1) log4 (3x+4)^5=15
(3x + 4)^5 = 4^15
(3x + 4)^5 = 1073741824
3x + 4 = 5√1073741824
3x + 4 = 64
3x = 60
x = 20
2) log (x^2-9)=log (5x+5)
As both sides logs
x^2 - 9 - 5x - 5 = 0
x^2 - 5x - 14 = 0
(x - 7)(x + 2) = 0
x - 7 = 0
x = 7
x + 2 = 0
x = -2
Hope this helps :-)

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for x , show work please. Can someone check my answers please.
1). log4 (3x+4)^5=15
2). log (x^2-9)=log (5x+5)
Here is a screenshot of them just incase. Link to screenshot : http://prntscr.com/a42nsg
my answer for #1 was no solution and my answer for #2 was x=7. Thanks !
1).
NOT QUITE!!
log+%284%2C+%283x+%2B+4%29%29%5E5+=+15
5+%2A+log+%284%2C+%283x+%2B+4%29%29+=+15 ------- Applying log+%28a%2C+b%29%5Ec+=+c+%2A+log+%28a%2C+%0D%0Ab%29
log+%284%2C+%283x+%2B+4%29%29+=+15%2F5 --------- Dividing by 5
log+%284%2C+%283x+%2B+4%29%29+=+3
3x+%2B+4+=+4%5E3 --------------- Converting to EXPONENTIAL form
3x + 4 = 64
3x = 64 - 4
3x = 60
x = 60%2F3, or highlight_green%28x+=+20%29
OR
log+%284%2C+%283x+%2B+4%29%29%5E5+=+15
%283x+%2B+4%29%5E5+=+4%5E15
%283x+%2B+4%29%5E5+=+%284%5E3%29%5E5
3x+%2B+4+=+4%5E3
3x+=+4%5E3+-+4
3x = 60
x = 60%2F3, or highlight_green%28x+=+20%29
2).
That's right!! Good job!!
log (x^2-9)= log (5x+5)
log+%28%28x%5E2+-+9%29%29+=+log+%28%285x+%2B+5%29%29
x%5E2+-+9+=+5x+%2B+5 ------ Applying log+%28a%29+=+log+%28b%29
x%5E2+-+5x+-+14+=+0
(x - 7)(x + 2) = 0
x = - 2 is ignored since it's an EXTRANEOUS solution
Therefore, highlight_green%28x+=+7%29