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nerdybill answered: 7009 problems
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logarithm/192209: 2log4-log3+logx-4=0
1 solutions

Answer 144252 by nerdybill(7011) About Me  on 2009-04-20 17:06:10 (Show Source):
You can put this solution on YOUR website!
2log4-log3+logx-4=0
log4^2-log3+logx-4=0
log(4^2/3)+logx-4=0
log(16/3)+logx-4=0
log(16(x-4)/3)=0
16(x-4)/3 = 10^0
16(x-4)/3 = 1
16(x-4) = 3
x-4 = 3/16
x = 3/16 + 4
x = 3/16 + 64/16
x = 67/16


logarithm/192193: Find the solution of the equation: 5Ln(1-x)= 8
1 solutions

Answer 144235 by nerdybill(7011) About Me  on 2009-04-20 16:13:00 (Show Source):
You can put this solution on YOUR website!
5Ln(1-x)= 8
Ln(1-x)^5= 8
(1-x)^5= e^8
1-x = fifthRoot(e^8)
1 = fifthRoot(e^8)+x
1 - fifthRoot(e^8) = x
1 - fifthRoot(2980.958) = x
1 - 4.953 = x
-3.953 = x


Polynomials-and-rational-expressions/192117: REDUCE EXPRESSION TO LOWEST TERMS
-2x-8/x^2+2x-8
1 solutions

Answer 144163 by nerdybill(7011) About Me  on 2009-04-20 11:06:26 (Show Source):
You can put this solution on YOUR website!
%28-2x-8%29%2F%28x%5E2%2B2x-8%29
Factoring numerator and denominator:
%28-2%28x%2B4%29%29%2F%28%28x%2B4%29%28x-2%29%29
.
Canceling terms, we get:
-2%2F%28x-2%29
.
Or, we could rewrite it as:
2%2F%282-x%29


Sequences-and-series/192065: This question is from textbook Saxon Algebra 2
Find a8 of a geometric sequence given that a3 = 32 and a5 = 512.
1 solutions

Answer 144125 by nerdybill(7011) About Me  on 2009-04-19 23:27:28 (Show Source):
You can put this solution on YOUR website!
You can review this site:
http://www.regentsprep.org/Regents/math/algtrig/ATP2/GeoSeq.htm
.
An = A1(r^(n-1))
.
The idea is that because they gave you:
a3 = 32 and a5 = 512
you can now find A1(first term) and r (the common ratio).
Now, you can find any term after that.
.
An = A1(r^(n-1))
32 = A1(r^2)
A1 = 32/r^2
.
An = A1(r^(n-1))
An = A1(r^4)
512 = (32/r^2)(r^4)
512 = 32(r^2)
16 = r^2
4 = r (common ratio)
.
A1 = 32/r^2 = 32/4^2 = 32/16 = 2 (first term)
.
An = A1(r^(n-1))
a8 = (2)(4^(8-1))
a8 = (2)(4^7)
a8 = 2*16384
a8 = 32768


Surface-area/192071: A farmer has 336 running feet of fence and wishes to form a rectangular pasture. One side of the pasture will be bounded by a very long wall, and so no fencing material will be needed for that side of the pasture. What should the dimensions of the pasture be if the area of the pasture is to be largest possible?

Could you please provide a detailed explanation of how you work the problem to find the solution. Thanks!

1 solutions

Answer 144123 by nerdybill(7011) About Me  on 2009-04-19 23:09:50 (Show Source):
You can put this solution on YOUR website!
A farmer has 336 running feet of fence and wishes to form a rectangular pasture. One side of the pasture will be bounded by a very long wall, and so no fencing material will be needed for that side of the pasture. What should the dimensions of the pasture be if the area of the pasture is to be largest possible?
.
Let x = width
and y = length
.
From the provided length of fencing available:
2x+y = 336
Solving for y:
y = 336-2x
.
Area = xy
Plugging in our value of y:
Area = x(336-2x)
Area = 336x-2x^2
Area = -2x^2 + 336x (parabola that opens downwards)
.
If we find the vertex, we'll find the maximum value of the width:
Area = -2x^2 + 336x
Area = -2(x^2 - 168x)
Area = -2(x^2 - 168x + 7056) + 14112
Area = -2(x - 84)^2 + 14112
Since the vertex is at (84, 14112)
we know the width is 84 feet
.
Length:
2x+y = 336
2(84)+y = 336
168+y = 336
y = 168 feet (length)
.
Dimension:
84 feet by 168 feet


Quadratic-relations-and-conic-sections/192073: Find the exact vertex of the parabola algebraically...

f(x) = (x - 1)^2 + (x + 3)

Could you please provide a detailed explantion of how you achieved the solution. Thanks!
1 solutions

Answer 144121 by nerdybill(7011) About Me  on 2009-04-19 22:57:21 (Show Source):
You can put this solution on YOUR website!
The "vertex form" is
y= a(x-h)2+k
where
(h,k) is the vertex
.
The idea is to make your equation look like that:
f(x) = (x - 1)^2 + (x + 3)
f(x) = (x - 1)(x - 1) + (x + 3)
f(x) = x^2 - 2x + 1 + x + 3
f(x) = x^2 - x + 4
Group x-terms:
f(x) = (x^2 - x) + 4
Complete the square:
f(x) = (x^2 - x + __ ) + 4
f(x) = (x^2 - x + 1/4 ) + 4 -1/4
f(x) = (x - 1/2)^2 + 16/4 -1/4
f(x) = (x - 1/2)^2 + 15/4
.
vertex = (1/2, 15/4)



Quadratic-relations-and-conic-sections/192074: Find the exact vertex of the parabola algebraically...

f(x) = -3x^2 + 5x + 1

Could you please provide a detailed explanation of how you achieved the solution. Thanks!
1 solutions

Answer 144120 by nerdybill(7011) About Me  on 2009-04-19 22:51:48 (Show Source):
You can put this solution on YOUR website!
The "vertex form" of a parabola is:
y= a(x-h)^2+k
where
(h,k) is the vertex
.
So, the idea is to manipulate the original equation into the "vertex form":
f(x) = -3x^2 + 5x + 1
First, group the x terms:
f(x) = (-3x^2 + 5x) + 1
Factor out a -3:
f(x) = -3(x^2 + (-5/3)x) + 1
Complete the square:
f(x) = -3(x^2 + (-5/3)x + __ ) + 1
f(x) = -3(x^2 + (-5/3)x + (25/36) ) + 1 + 25/12
f(x) = -3(x - 5/6 )^2 + 12/12 + 25/12
f(x) = -3(x - 5/6 )^2 + 37/12 (this is the vertex form)
.
Vertex = (5/6, 37/12)


Angles/191952: Two angles atre complementary. The sum of the measure of the first angle and one-fourth the second angle is 69 degrees. Find the measure of the angles.
1 solutions

Answer 144017 by nerdybill(7011) About Me  on 2009-04-19 12:24:32 (Show Source):
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Two angles atre complementary. The sum of the measure of the first angle and one-fourth the second angle is 69 degrees. Find the measure of the angles.
.
Two angles are complementary if their sum equals 180 degrees.
.
Let x = measure of second angle
then
180-x = measure of first angle
.
(180-x) + (1/4)x = 69
720 - 4x + x = 276
720 - 3x = 276
-3x = -444
x = 148 degrees (second angle)
.
First angle:
180-x = 180-148 = 32 degrees (first angle)


Word_Problems_With_Coins/191932: I always save my change week to week. This week I found all nickels and dimes. There were twice as many dimes as nickles and the value of the dimes was $.90 more than the value of the nickles. How many nickles and dimes do I have?
I THINK I KNOW THE ANSWERS BUT I AM HAVING TROUBLE COMING UP WITH THE CORRECT WAY TO WRITE IT. PLEASE HELP!!
1 solutions

Answer 144013 by nerdybill(7011) About Me  on 2009-04-19 11:05:45 (Show Source):
You can put this solution on YOUR website!
There were twice as many dimes as nickles and the value of the dimes was $.90 more than the value of the nickles.
.
Let n = number of nickels
then
2n = number of dimes
.
.10(2n) = .05n + .90
.20n = .05n + .90
.15n = .90
n = .90/.15
n = 6 (nickels)
.
Dimes:
2n = 2(6) = 12 (dimes)


Polynomials-and-rational-expressions/191938: This question is from textbook College Algebra A Graphing Approach
#8. x^4 + 5x^2 -36 = 0
I started working this problem and then got confused. If you could help with this. Thanks
1 solutions

Answer 144011 by nerdybill(7011) About Me  on 2009-04-19 11:02:37 (Show Source):
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x^4 + 5x^2 -36 = 0
Factoring:
(x^2+9)(x^2-4) = 0
.
Setting each term to zero:
(x^2+9) = 0
x^2 = -9
x = sqrt(-9)
x = +- 3i
.
(x^2-4) = 0
x^2 = 4
x = sqrt(4)
x = +- 2


Linear_Algebra/191935: This question is from textbook
How are addition and multiplication used to solve a linear equation? Demonstrate by solving "12x + 6 = 31 – 2x" Thank You!
1 solutions

Answer 144009 by nerdybill(7011) About Me  on 2009-04-19 10:58:54 (Show Source):
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To solve a linear equation, isolate the unknown to one side of the equat
ion.
.
12x + 6 = 31 – 2x
.
Start by moving all the x terms to the left. Do this by ADDING 2x to both sides:
12x + 6 + 2x = 31 – 2x + 2x
14x + 6 = 31
.
Next, subtract 6 from both sides:
14x + 6 - 6 = 31 - 6
14x = 25
.
Finally, MULTIPLY both sides by (1/14):
(1/14)14x = 25(1/14)
x = 25/14 (solution for x)


Linear-systems/191921: Find the slope and y-intercept 0f 3x-5y+5=0. Show answers in fractions.
1 solutions

Answer 143999 by nerdybill(7011) About Me  on 2009-04-19 10:04:19 (Show Source):
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Manipulate the equation into the "slope-intercept" form:
y = mx + b
where
m is slope
b is the y-intercept
.
3x-5y+5=0
3x-5y= -5
-5y= -3x -5
5y= 3x + 5
y = (3/5)x + (5/5)
y = (3/5)x + 1
.
By inspection, based on the "slope-intercept" form we have:
slope is 3/5
y-intercept is at (0,1)


Polynomials-and-rational-expressions/191928: I need some help with subtracting this polynomial:
(-8c^2+4c+2)-(6c^2+2)
Thank you again!

1 solutions

Answer 143998 by nerdybill(7011) About Me  on 2009-04-19 09:59:39 (Show Source):
You can put this solution on YOUR website!
(-8c^2+4c+2)-(6c^2+2)
.
Distribute the negative to terms inside the right parenthesis:
-8c^2+4c+2-6c^2-2
.
Group like-terms:
(-8c^2-6c^2)+4c+(2-2)
.
Combine:
(-14c^2)+4c+(0)
.
-14c^2+4c
Or, factoring out 2c:
2c(-7c + 2)


Geometry_Word_Problems/191931: The area of a rectangle is 64cm^2. Its length is 4times the width. What is its length and width? THANK YOU TO WHO EVER HELPS ME WITH THIS. THANK YOU THANK YOU THANK YOU.
1 solutions

Answer 143996 by nerdybill(7011) About Me  on 2009-04-19 09:55:43 (Show Source):
You can put this solution on YOUR website!
The area of a rectangle is 64cm^2. Its length is 4times the width. What is its length and width
.
Let w = width
then
4w = length
.
w(4w) = 64
4w^2 =64
w^2 = 16
w = 4 cm (width)
.
Length:
4w = 4(4) = 16 cm (length)


Polynomials-and-rational-expressions/191880: I need help again, please help me add:
(2x^2-3xy+y^2)+(-8x^2-8xy-y^2)+(x^2+xy-4Y^2)
Thank you soooooooo much!!!
1 solutions

Answer 143979 by nerdybill(7011) About Me  on 2009-04-19 00:39:46 (Show Source):
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(2x^2-3xy+y^2)+(-8x^2-8xy-y^2)+(x^2+xy-4Y^2)
.
Remove parentheses:
2x^2-3xy+y^2-8x^2-8xy-y^2+x^2+xy-4Y^2
.
Group like-terms:
(2x^2-8x^2+x^2)+(-3xy-8xy+xy)+(y^2-y^2-4Y^2)
.
Combine like-terms:
(-5x^2)+(-10xy)+(-4Y^2)
-5x^2-10xy-4Y^2
or
-(5x^2+10xy+4Y^2)


Expressions-with-variables/191891: 13+a=25+b
b-a= ?
1 solutions

Answer 143978 by nerdybill(7011) About Me  on 2009-04-19 00:31:08 (Show Source):
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Isolate "b-a" to one side of the equation.
.
If you started with:
13+a=25+b
Subtract 'a' from both sides:
13 = 25+b-a
Now, subtract 25 from both sides:
13-25 = b-a
-12 = b-a (this is what they're looking for)


Percentage-and-ratio-word-problems/191866: If jan can paint a house in 4 hours and jim can paint a house in 6 hours, how long will it take for them to paint the house together.
1 solutions

Answer 143973 by nerdybill(7011) About Me  on 2009-04-18 21:24:28 (Show Source):
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If jan can paint a house in 4 hours and jim can paint a house in 6 hours, how long will it take for them to paint the house together.
.
Let x = hours for both to paint house
then
x(1/4 + 1/6) = 1
x/4 + x/6) = 1
6x + 4x = 24
10x = 24
x = 2.4 hours
or
2 hours and 24 minutes


Linear-equations/191860: Find the slope -intercept equation of the line that has the given characteristics
slope 3 and y -intercept (0,9)
1 solutions

Answer 143962 by nerdybill(7011) About Me  on 2009-04-18 19:07:49 (Show Source):
You can put this solution on YOUR website!
Find the slope -intercept equation of the line that has the given characteristics
slope 3 and y -intercept (0,9)
.
The "slope-intercept" form of a line is
y = mx + b
where
m is slope
b is the y-intercept
.
Therefore, for:
slope 3 and y -intercept (0,9)
we have
y = 3x + 9 (this is what they're looking for)


Functions/191837: Which relation is also a function?
A) (3,-3), (4,-3), (2,-3)
B) (1,7), (8,4), (-3,-4), (1,4)
C) (2,0), (2,3), (2,8), (2,-3)
D) (1,-1), (0,0), (1,0), (0,-1)
1 solutions

Answer 143951 by nerdybill(7011) About Me  on 2009-04-18 16:36:41 (Show Source):
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For it to be a function, for any value of 'x', there should only be one value of 'y',.
.
The ONLY answer that fits would be: A.


Equations/191845: how can the number 45 be divided into two parts so that 4 times one part is 9 less than 5 times the other?
1 solutions

Answer 143950 by nerdybill(7011) About Me  on 2009-04-18 16:33:48 (Show Source):
You can put this solution on YOUR website!
how can the number 45 be divided into two parts so that 4 times one part is 9 less than 5 times the other?
.
Let x = first part
then
45-x = second part
.
4(45-x) = 5x-9
180 - 4x = 5x-9
180 = 9x-9
189 = 9x
21 = x (first part)
.
Second part:
45-x = 45-21 = 24 (second part)


Triangles/191808: This question is from textbook Beginning Algebra
The area of a triangle is 30 square inches. The base of the triangle measures 2 inches more than twice the height of a triangle. Find the measures of the base and the height.
1 solutions

Answer 143929 by nerdybill(7011) About Me  on 2009-04-18 08:35:14 (Show Source):
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The area of a triangle is 30 square inches. The base of the triangle measures 2 inches more than twice the height of a triangle. Find the measures of the base and the height.
.
Area of any triangle = (1/2)bh
where
b is base
h is height
.
Let h = height
then
2h+2 = base
.
30 = (1/2)(2h+2)h
30 = (h+1)h
30 = h^2+h
0 = h^2+h-30
0 = (h+6)(h-5)
.
h ={-6,5}
We can toss out the negative solution leaving us with:
h = 5 inches
.
base:
2h+2 = 2(5)+2 = 10+2 = 12 inches
.
Therfore,
height is 5 inches
base is 12 inches


Quadratic_Equations/191715: solve quadratic equation
x^2=6x-3
1 solutions

Answer 143823 by nerdybill(7011) About Me  on 2009-04-17 16:44:56 (Show Source):
You can put this solution on YOUR website!
x^2=6x-3
Move all terms to the left:
x^2-6x+3 = 0
Since we can't factor, we must resort to the quadratic equation.
Doing so, yields two solutions:
x = {5.449, 0.551}
.
Details of quadratic equation follows:
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-6x%2B3+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-6%29%5E2-4%2A1%2A3=24.

Discriminant d=24 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--6%2B-sqrt%28+24+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-6%29%2Bsqrt%28+24+%29%29%2F2%5C1+=+5.44948974278318
x%5B2%5D+=+%28-%28-6%29-sqrt%28+24+%29%29%2F2%5C1+=+0.550510257216822

Quadratic expression 1x%5E2%2B-6x%2B3 can be factored:
1x%5E2%2B-6x%2B3+=+1%28x-5.44948974278318%29%2A%28x-0.550510257216822%29
Again, the answer is: 5.44948974278318, 0.550510257216822. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-6%2Ax%2B3+%29


Equations/191718: Can you please help me solve this equation?
5(-2x+1)= -9(x+1)
Thank you so very much!
1 solutions

Answer 143822 by nerdybill(7011) About Me  on 2009-04-17 16:39:59 (Show Source):
You can put this solution on YOUR website!
5(-2x+1)= -9(x+1)
Distributing on the left and right side:
-10x+5= -9x-9
5= x-9
14 = x


Linear-systems/191714: Hi there, I need some help again. Can someone help me solve this? I don't even understand the problem. Thanks! The perimeter of a rectangle is 108m. The length is 9m more then twice the width find the dimensions. What is the length.
1 solutions

Answer 143820 by nerdybill(7011) About Me  on 2009-04-17 16:38:02 (Show Source):
You can put this solution on YOUR website!
Hi there, I need some help again. Can someone help me solve this? I don't even understand the problem. Thanks! The perimeter of a rectangle is 108m. The length is 9m more then twice the width find the dimensions. What is the length.
.
Let w = width of rectangle
then
2w+9 = length of rectangle
.
2(width + length) = perimeter
.
2(w + 2w+9) = 108
2(3w+9) = 108
6w+18 = 108
6w = 90
w = 16 m
.
length:
2w+9 = 2(16)+9 = 32+9 = 41 m


Equations/191662: logx(1/16)=-4
the log x, the x is suppose to be under the log.
here are the choices:
a. 2
b. 1/4
c. 4
d. 1/2

1 solutions

Answer 143791 by nerdybill(7011) About Me  on 2009-04-17 10:08:02 (Show Source):
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.
logx(1/16)=-4
1/16 = x^(-4)
1/16 = 1/x^4
Cross multiplying:
x^4 = 16
x = fourth root (6)
x = 2
.
Answer: a


Equations/191663: Given f(x) = log5 x , find f(1/25)
here are the choices:
a. 5
b. -5
c. 1/5
d. -2
1 solutions

Answer 143790 by nerdybill(7011) About Me  on 2009-04-17 10:05:32 (Show Source):
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.
f(x) = log5 x
f(1/25) = log5 (1/25)
f(1/25) = log5(1) - log5(25)
f(1/25) = log5(5^0) - log5(5^2)
f(1/25) = 0 - 2
f(1/25) = -2
.
Answer: d.


Quadratic_Equations/191655: Solve by completing the square. First divide to make sure that the coefficient of x^2 is 1
9x^2+18x=-8
I completed the square but dividing to make sure that the coefficient is 1 I am not understanding. Here is what I did...
9x^2+18x+8=0
(3x+4)(3x+2)
3x+4=0 3x+2=0
3x=-4 3x=-2
x=-4/3 x=-2/3
1 solutions

Answer 143787 by nerdybill(7011) About Me  on 2009-04-17 09:34:23 (Show Source):
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Although your answer is correct, you solved it by factoring instead of "completing the square".
.
9x^2+18x=-8
.
9(x^2+2x) = -8
9(x^2+2x+__) = -8
Take half the 'b' term and square it. Then balance the right with what you just added to the left side.
9(x^2+2x+1) = -8 + 9
9(x+1)^2 = 1
Dividing both sides by 9:
(x+1)^2 = 1/9
Taking the square root of both sides:
(x+1) = +-(1/3) (that's plus or minus 1/3)
x = +-(1/3) - 1
.
x = 1/3 - 1 = 1/3 - 3/3 = -2/3
x = -1/3 - 1 = -1/3 - 3/3 = -4/3
.
x = {-4/3, -2/3}


Money_Word_Problems/191654: The total profit for a company in October was 16% higher than it was in September. The total profit for the two months was $507,600. Find the profit for each month.
1 solutions

Answer 143786 by nerdybill(7011) About Me  on 2009-04-17 09:25:49 (Show Source):
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The total profit for a company in October was 16% higher than it was in September. The total profit for the two months was $507,600. Find the profit for each month.
.
Let x = profit for September
then
1.16x = profit of October
.
x + 1.16x = 507600
x(1+1.16) = 507600
x(2.16) = 507600
x = 507600/2.16
x = $235,000 (September)
.
October:
1.16x = 1.16(235000) = $272,600 (October)


expressions/191650: please help me evaluate this problem

What is d(3a+c)

if a is -2..if b= -1 c= 2 abd d= one fourth

thanks
1 solutions

Answer 143785 by nerdybill(7011) About Me  on 2009-04-17 09:21:54 (Show Source):
You can put this solution on YOUR website!

What is d(3a+c)
if a is -2..if b= -1 c= 2 abd d= one fourth
.
Simply "plug in" the provided values:
d(3a+c)
= (1/4)(3(-2)+2)
= (1/4)(-6+2)
= (1/4)(-4)
= -1
.
Don't know why a value for 'b' was provided...
.


Rate-of-work-word-problems/191642: Andrea can rake her Dad's yard in 45 minutes. Andrea's brother Bradford rakes one and one-half times faster than Andrea. How long would it take them to rake their Dad's yard together?
1 solutions

Answer 143779 by nerdybill(7011) About Me  on 2009-04-17 05:12:47 (Show Source):
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Andrea can rake her Dad's yard in 45 minutes. Andrea's brother Bradford rakes one and one-half times faster than Andrea. How long would it take them to rake their Dad's yard together?
.
Andrea's rate:
1 job per 45 minutes
.
Brother's rate:
1.5x = 45
x = 45/1.5
x = 1 job per 30 minutes
.
Let t = time (in hours) it would take for them to work together
then
(1/45)t + (1/30)t = 1
30t + 45t = 1350
75t = 1350
t = 1350/75
t = 18 minutes


Exponential-and-logarithmic-functions/191417: lnx - ln(x + 2) = 3
This is what I tried:
lnx - ln(x+2) = 3
distributed
lnx - lnx - ln2 = 3
these cancel out leaving...
-LN2 = 3
DIVIDE BOTH SIDES BY -LN2
the answer seems wrong.
1 solutions

Answer 143658 by nerdybill(7011) About Me  on 2009-04-16 03:51:55 (Show Source):
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Review log rules:
.
lnx - ln(x + 2) = 3
ln [(x)/(x+2)] = 3
(x)/(x+2) = e^3
x = e^3(x+2)
x = e^3x+2e^3
x-e^3x = 2e^3
x(1-e^3) = 2e^3
x = 2e^3/(1-e^3)