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Tutors Answer Your Questions about logarithm (FREE)
Question 104685: Could someone please assist me by solving this logarithmic equation step-by-step for future reference. Thank you.
log(7y + 1) = 2log(y+3)-log2
log(7y + 1) = log(y+3)^2-log2
log(7y + 1) = log(y+3)^2/2
you can write
(7y + 1) = (y+3)^2/2
2(7y + 1) = y^2+6y+9
14y+2=y^2+6y+9
y^2-8y+7=0
y1=(8+rootsquare(36))/2
=(8+6)/2
=7
y2=(8-rootsquare(36))/2
=(8-6)/2
=1
so (y1,y2) are (7,1)
Click here to see answer by scott8148(3382)   |
Question 104685: Could someone please assist me by solving this logarithmic equation step-by-step for future reference. Thank you.
log(7y + 1) = 2log(y+3)-log2
log(7y + 1) = log(y+3)^2-log2
log(7y + 1) = log(y+3)^2/2
you can write
(7y + 1) = (y+3)^2/2
2(7y + 1) = y^2+6y+9
14y+2=y^2+6y+9
y^2-8y+7=0
y1=(8+rootsquare(36))/2
=(8+6)/2
=7
y2=(8-rootsquare(36))/2
=(8-6)/2
=1
so (y1,y2) are (7,1)
Click here to see answer by bimanewton(8)  |
Question 104905: Hi there,
I'm completely stumped. I need to solve for X:
(9^(2x))*(27^(x-3))=1/9
I graphed it, and know that the answer SHOULD be -11, but I need to see HOW to do the problem.
Thank you,
Brad Easler
Click here to see answer by duggie(22) |
Question 106373: Please help me with this expression: logA/logB = A/B = 2/3. The correct answer is 2/3. It was solved correctly to = 2/3. The logs were canceled which is not a proper method of using logs. I need to know what A and B are so that logA/logB = 2/3.
I think the problem can be set up to look like: logA = log 2x and logB = log 3x. So, log2x/log3x = 2x/3x.
Click here to see answer by stanbon(26252) |
Question 106845: Could you please take the time to help me solve this problem: Solve g(x) = 0 for x, if g(x) = log x + log x2 + 8 log x – log x3 – 16. Note that all logarithmic functions are to the base 10. Show your work.
Thank you for helping me
Click here to see answer by Fombitz(2113)  |
Question 107974This question is from textbook Precalculus
: Hi,
Please help me solve: S(t)=200[1-(0.86)^t]
I've used the 10 hours for time to start S(10)
and the result I have is S(10)=200[14].
I haven't found out what to do with the brackets or what they mean.
I am also supposed to turn this into an exponetial and and logarithmic function for graphing. But I'm stuck at the start.
I need this solved for an overdue assignment - Please help!
Thanks,
MarisaThis question is from textbook Precalculus
Click here to see answer by edjones(3291)  |
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