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test/152091: This question is from textbook Algebra 1 An Incremental Development
Solve and graph: 2 - |x| ≥ -2, D = {Integers}
1 solutions

Answer 111793 by Nate(3495) About Me  on 2008-08-15 16:54:30 (Show Source):
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2 - |x| ≥ -2
-|x| ≥ -4
|x| ≤ 4
x ≤ 4 and x ≥ -4
4 ≥ x ≥ -4




Word_Problems_With_Coins/149502: what is the equation for this problem. A man has a job for thirty days, he will be paid 1 penny for the first day, 2 pennies for the second day, 4 pennies for the third day, and so on. What is the equation that would give the total amount of pennies for the 30th day?
this is not in the text book I have.
1 solutions

Answer 109683 by Nate(3495) About Me  on 2008-07-23 21:15:48 (Show Source):
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This is actually a geometric sum or series.
S = a1(1 - r^n)/(1 - r)
S: sum, a1: first term, r: rate, n: # of terms
A man has a job for thirty days, he will be paid 1 penny for the first day, 2 pennies for the second day, 4 pennies for the third day, and so on. What is the equation that would give the total amount of pennies for the 30th day?
1 + 2 + 4 + 8 + ... a1 * r^(n - 1) or 2^(n - 1)
a1 = 1, r = 2, n = 30
S = (1 - 2^30)/(1 - 2) = 1,073,741,823 pennies or $10,737,418.23


logarithm/149218: Find y as a function of x. The constant Cis a positive number.
ln(y-3)=ln 2(x^2)+ln C
1 solutions

Answer 109500 by Nate(3495) About Me  on 2008-07-22 16:15:56 (Show Source):
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ln( y - 3 ) = ln( 2x^2 ) + ln( C )
ln( y - 3 ) = ln( 2C*x^2 )
y - 3 = 2C*x^2
y = 2C*x^2 + 3


Geometric_formulas/148843: Verify the identity using multiple-angle formulas.

1a) cos^(2)3x-sin^(2)3x=cos6x


1b) (sin^(2)2α)/(sin^(2)α)=4-4sin^(2)α
1 solutions

Answer 109258 by Nate(3495) About Me  on 2008-07-20 17:22:08 (Show Source):
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cos^2(3x) - sin^2(3x) = cos(6x)
cos^2(3x) - sin^2(3x) = cos(3x + 3x)
cos^2(3x) - sin^2(3x) = cos(3x)cos(3x) - sin(3x)sin(3x)
~
sin^2(2α) / sin^2(α) = 4 - 4sin^2(α)
sin(2α)sin(2α) / sin^2(α) = 4 - 4sin^2(α)
2sin(α)cos(α)2sin(α)cos(α) / sin^2(α) = 4 - 4sin^2(α)
4cos^2(α) = 4 - 4sin^2(α)
4(1 - sin^2(α)) = 4 - 4sin^2(α)


Trigonometry-basics/148894: Which of the following statements is true?

When rotating a conic section, combinations of sin? and cos? are often used
When rotating a conic section, only sin? needs to be used
Conic sections can neither be rotated nor translated
Conic sections can be rotated but not translated
1 solutions

Answer 109257 by Nate(3495) About Me  on 2008-07-20 17:15:15 (Show Source):
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When rotating a conic section, combinations of sin? and cos? are often used ~ yes, each is used
When rotating a conic section, only sin? needs to be used ~ no, cosine is used as well
Conic sections can neither be rotated nor translated ~ no, they can be rotated and moved
Conic sections can be rotated but not translated ~ no, they can be rotated and moved


Geometry_proofs/148912: Verify the identity using Aultiple-Angle Trigonometric formulas.

1a) cos^(4)x-sin^(4)x=cos2x



1b) tanθ+cotθ=2csc2θ
1 solutions

Answer 109256 by Nate(3495) About Me  on 2008-07-20 17:12:44 (Show Source):
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cos^4(x) - sin^4(x) = cos(2x)
cos^4(x) - sin^4(x) = 2cos^2(x) - 1
( cos^2(x) + sin^2(x) )( cos^2(x) - sin^2(x) ) = 2cos^2(x) - 1
( cos^2(x) + 1 - cos^2(x) )( cos^2(x) - ( 1 - cos^2(x) ) ) = 2cos^2(x) - 1
( 1 )( 2cos^2(x) - 1 ) = 2cos^2(x) - 1
~
tan(θ) + cot(θ) = 2csc(2θ)
tan(θ) + cot(θ) = 2/sin(2θ)
tan(θ) + cot(θ) = 1/sin(θ)cos(θ)
sin(θ)/cos(θ) + cos(θ)/sin(θ) = 1/sin(θ)cos(θ)
sin^2(θ)/cos(θ)sin(θ) + cos^2(θ)/sin(θ)cos(θ) = 1/sin(θ)cos(θ)
( sin^2(θ) + cos^2(θ) )/sin(θ)cos(θ) = 1/sin(θ)cos(θ)
1/sin(θ)cos(θ) = 1/sin(θ)cos(θ)


Geometry_proofs/148679: Find the solutions of the equation that are in the interval [0,2π). Please show steps (especially rearranging the equation to solve it. Thanks for helping me. I know the solutions are 11π/6, π/2 but I just can't
figure out how to isolate to get those solutions. Thanks again.

1) 1-sint=(√3)cost
1 solutions

Answer 109087 by Nate(3495) About Me  on 2008-07-18 16:02:54 (Show Source):
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1 - sin(t) = √3)cos(t)
1 - 2sin(t) + sin^2(t) = 3cos^2(t)
1 - 2sin(t) + sin^2(t) = 3(1 - sin^2(t))
1 - 2sin(t) + sin^2(t) = 3 - 3sin^2(t)
4sin^2(t) - 2sin(t) - 2 = 0
2sin^2(t) - sin(t) - 1 = 0
(2sin(t) + 1)(sin(t) - 1) = 0
2sin(t) + 1 = 0 and sin(t) - 1 = 0
sin(t) = -1/2 and sin(t) = 1


Geometry_proofs/148653: Find the solutions of the equation that are in the interval [0,2π). Please show steps (especially rearranging the equation to solve it. Thanks for helping me. I know the solution is 7pi/6, 11pi/6, pi/2.
sinb+2cos^(2)b=1

1 solutions

Answer 108988 by Nate(3495) About Me  on 2008-07-17 16:49:23 (Show Source):
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sin(b) + 2cos^2(b) = 1
sin(b) + 2(1 - sin^2(b)) = 1
sin(b) + 2 - 2sin^2(b) = 1
2sin^2(b) - sin(b) - 1 = 0
* when you factor, you treat this much like any other polynomial .. for understanding sakes, x = sin(b)
2x^2 - x - 1 = 0
2x^2 - 2x + x - 1 = 0
(2x^2 - 2x) + (x - 1) = 0
2x(x - 1) + (x - 1) = 0
(2x + 1)(x - 1) = 0
* x = sin(b)
(2sin(b) + 1)(sin(b) - 1) = 0
2sin(b) + 1 = 0 and sin(b) - 1 = 0
sin(b) = -1/2 and sin(b) = 1


Angles/148271: to the nearest tenth of a degree, find the sizes of the acute angles in the right triangle whose hypotenuse is 2.5 times as long as its short leg.
1 solutions

Answer 108674 by Nate(3495) About Me  on 2008-07-14 18:50:03 (Show Source):
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Let's begin with angle O. We need a trig identity that would include the opposite leg and the hypotenuse. _SOH_ CAH TOA
sin O = x / 2.5x
sin O = 1 / 2.5
sin O = 0.4
O = 23.6 degrees
Angle Q = 90 - Angle O
Angle Q = 90 - 23.6
Angle Q = 66.4 degrees


Angles/148270: Judy is driving along a highway that is climbing a steady 9-degree slope. After driving for 2 miles along this road, how much altitude has Judy gained?
How far must she travel in order to gain a mile of altitude?
thank you very much!
1 solutions

Answer 108672 by Nate(3495) About Me  on 2008-07-14 18:43:28 (Show Source):
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Judy is driving along a highway that is climbing a steady 9-degree slope. After driving for 2 miles along this road, how much altitude has Judy gained?

This has to do with a leg and the hypotenuse, so tangent is ruled out. Since this involves the opposite leg and the hypotenuse, sine is required.
sin( 9* ) = x / 2
x = 0.31 miles
How far must she travel in order to gain a mile of altitude?

sin( 9* ) = 1 / x
x = 6.39 miles


Exponents/147981: solve for x
x^x^x^x^.....x^3 = 3
1 solutions

Answer 108365 by Nate(3495) About Me  on 2008-07-12 09:46:15 (Show Source):
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x^x^x^x^.....x^3 = 3
log( x^x^x^x^.....x^3 ) = log( 3 )
x^x^x^.....x^3 * log( x ) = log( 3 )
3 * log( x ) = log( 3 )
log( x ) = log( 3 )/3
x = 10^( log( 3 )/3 )
About 1.4422


Exponential-and-logarithmic-functions/147815: h(x)e^-x Description of transformation, Equations for the Horizontal Asymptote, y-intercept in (x,y) form. I am not sure how to do this one becuase of the -x? Help
1 solutions

Answer 108363 by Nate(3495) About Me  on 2008-07-12 09:42:04 (Show Source):
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e^-x = 1 / e^x
Transformation: (x,y) ~> (-x,y) so flip about y-axis
Horizontal asymptote is the value for y when x approaches infinity, or increases indefinately.
1 / e = 0.37
1 / e^2 = 0.14
1 / e^3 = 0.05
1 / e^4 = 0.02
Horizontal Asymptote: y = 0
Y-intercept as coordinates (0,y)
y = 1 / e^x
y = 1 / e^0
y = 1
So: (0,1)


Trigonometry-basics/147846: trig identities- i need help proving that this identity is true
(sin2x/ 1+cos2x) * (cosx/1+cosx) = tan(x/2)
1 solutions

Answer 108232 by Nate(3495) About Me  on 2008-07-10 19:12:32 (Show Source):
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Equations/147685: If g(x) is a logarithmic function, then what effect does 'c' have on g(x) if f(x) = g(cx)?
a. g(x) shifts c units to the sign opposite of c
b. g(x) stretches or shrinks horizontally
c. g(x) stretches vertically
d. There is no effect on g(x)

1 solutions

Answer 108075 by Nate(3495) About Me  on 2008-07-09 14:09:31 (Show Source):
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b.)
For example:
g(x) = 1 / x
g(3x) = 1 / (3x) or g(x/3) = 3 / x


Equations/147691: If log 2 ≈ 0.301 and log 3 ≈ 0.477, then log 6 ≈
a. 0.778
b. 0.144
c. 0.176
d. Cannot be determined given this information

1 solutions

Answer 108073 by Nate(3495) About Me  on 2008-07-09 14:07:16 (Show Source):
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log 6
log 2*3
log 2 + log 3
0.301 + 0.477
0.778
a.)


Money_Word_Problems/147693: There are 20 kilograms of a solution that is 10% salt. How many kilograms of salt must be added to make a solution that is 25% salt?
1 solutions

Answer 108071 by Nate(3495) About Me  on 2008-07-09 14:06:06 (Show Source):
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( 20 * 10% + x * 100% ) / ( 20 + x ) = 25%
( 20 * 0.1 + x ) / ( 20 + x ) = 0.25
( 2 + x ) / ( 20 + x ) = 0.25
2 + x = 0.25( 20 + x )
2 + x = 5 + 0.25x
0.75x = 3
x = 4kg salt


Equations/147694: y = log π is equivalent to:
a. 10^-y = π
b. 10^π = y
c. 10^y = π
d. Cannot be defined without first knowing the base of the logarithm

1 solutions

Answer 108069 by Nate(3495) About Me  on 2008-07-09 14:03:08 (Show Source):
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y = log π
10^y = 10^log π
* 10^log π = π
10^y = π
c.)


Mixture_Word_Problems/147618: eighty liters of a 40% antifreeze solution had to be strengthened so it contained 52% antifreeze. how much should be added?
1 solutions

Answer 107990 by Nate(3495) About Me  on 2008-07-08 21:19:09 (Show Source):
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I'm guessing you are adding 100% or pure antifreeze.
( 80 * 40% + x * 100% ) / ( 80 + x ) = 52%
( 32 + x ) / ( 80 + x ) = 0.52
32 + x = 0.52( 80 + x )
32 + x = 41.6 + 0.52x
0.48x = 9.6
x = 20 Litres of antifreeze


Complex_Numbers/147558: I'm not quite sure how to simplify the expression 4 over 2+5i (4/2+5i) and I'm not quite sure what i to the -35th power means.
1 solutions

Answer 107944 by Nate(3495) About Me  on 2008-07-08 13:56:51 (Show Source):
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i^(-35)
1/i^35
1/( i * i^34 ) ~ you want an even power
1/( i * (i^2)^17 ) ~ now, you want an exponent of 2
1/( i * (-1)^17 ) ~ i^2 = -1
-1 / i ~ (-1)^17 = -1
..
4 / (2 + 5i)
4(2 - 5i) / (2 + 5i)(2 - 5i) ~ multiply the num. and dem. by the conjugate


Equations/147551: If R(x) is a rational function, then R(x) < 0 describes what?
a. Values of x that make R(x) positive in value
b. Values of R(x) that make x negative in value
c. Values of x that make R(x) negative in value
d. Negative values of x that make R(x) also negative
1 solutions

Answer 107928 by Nate(3495) About Me  on 2008-07-08 12:40:26 (Show Source):


Equations/147553: What is a requirement of the coefficients of a polynomial in order to use the Rational Zero Theorem?
a. That they are all non-negatives
b. That they are all interger values
c. That they are all whole numbers
d. That they are all non-negative integers
1 solutions

Answer 107927 by Nate(3495) About Me  on 2008-07-08 12:39:22 (Show Source):


Equations/147552: How many positive real solutions are there in:
f(x) = -2x^4 + 3x^3 + 7x^2 + 2
a. 0
b. 2
c. 1
d. None, there is no x-term
1 solutions

Answer 107926 by Nate(3495) About Me  on 2008-07-08 12:38:40 (Show Source):
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c.
because there is only one sign change for f(x)


Linear-equations/147443: 26) Find values of m and b in the following system so that the solution to the system is (-3,4).
5x+7y=b
mx+y=22

Can someone please show how to solve this problem. I am stuck.
v/r

1 solutions

Answer 107815 by Nate(3495) About Me  on 2008-07-07 10:47:43 (Show Source):
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Plug x = -3 and y = 4 into each:
-15 + 28 = b
-3m + 4 = 22
so:
13 = b
m = -6
now:
5x + 7y = 13
-6x + y = 22


absolute-value/147446: 1. |x | = 6

2. |3x + 2| = 14

3. - 5| x + 1| = -10

4. |x - 2| + 10 = 12

5. |x| = - 5

6. |2x + 6| - 4 = 20

7. 6 - 3|2x + 6| = 0

8. 10 - |x + 2| = 12

1 solutions

Answer 107814 by Nate(3495) About Me  on 2008-07-07 10:44:27 (Show Source):
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There are two answers: solving normally, and solving when you negate
1. | x | = 6
x = 6 and x = -6
2. |3x + 2| = 14
3x + 2 = 14 and 3x + 2 = -14
3x = 12 and 3x = -16
x = 4 and x = -16/3
3. -5| x + 1 | = -10
| x + 1 | = 2
x + 1 = 2 and x + 1 = -2
x = 1 and x = -3
... and so on ...


Radicals/147444: Consider the equation 4x^2 – 4x + 5 = 0.
(i) Compute the discriminant, b2 – 4ac, and then state whether one real-number solution, two different real-number solutions, or two different imaginary-number solutions exist.
(ii) Use the quadratic formula to find the exact solutions of the equation.


1 solutions

Answer 107813 by Nate(3495) About Me  on 2008-07-07 10:36:43 (Show Source):
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4x^2 – 4x + 5 = 0
4x^2 + (-4)x + 5 = 0
ax^2 + bx + c = 0
a = 4
b = -4
c = 5
(i) Compute the discriminant, b2 – 4ac, and then state whether one real-number solution, two different real-number solutions, or two different imaginary-number solutions exist.
disc. > 0 ~ two real
disc. = 0 ~ one real
disc. < 0 ~ two imaginary
(ii) Use the quadratic formula to find the exact solutions of the equation.


Triangles/147336: Given isosceles triangle ABC where AB = BC = 10 and the altitude from B has length 4. Find the length of the base.

Thanks so much, I really don't understand altitude problems.
1 solutions

Answer 107714 by Nate(3495) About Me  on 2008-07-06 12:38:52 (Show Source):
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The altitude makes a right triangle:
a^2 + b^2 = c^2
a^2 + 4^2 = 10^2
a^2 + 16 = 100
a^2 = 84
a = 2*sqrt(21)
Base is twice "a":
AC = 4*sqrt(21)


Functions/147317: I need to find out what the population would be 4 years from now. The population is 45,103,674 and the growth rate if 1.40%.

1 solutions

Answer 107690 by Nate(3495) About Me  on 2008-07-06 10:22:41 (Show Source):
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A = P*(1 + r)^t
A = 45,103,674*(1.014)^4


Equations/147301: How do I solve the equation 2x^2 + 3x + 6 = 0
1 solutions

Answer 107677 by Nate(3495) About Me  on 2008-07-06 07:23:39 (Show Source):
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You first try to factor the quadratic:
2x^2 + 3x + 6 = 0
We need factors of 2 * 6 or 12 that sum to 3, which there are none.
The simplest way from here is to use the quadratic formula:

.

The solution is imaginary because of sqrt( negative ) .. you can simplify from here.


Sequences-and-series/147003: Can someone help me with this, not sure how to go about this...
Using the formula, n^2=(k(k+1)(2k+1))/6 compute the value of
where m=0 and 5

1 solutions

Answer 107675 by Nate(3495) About Me  on 2008-07-06 07:17:28 (Show Source):


Points-lines-and-rays/147269: Given that (-1,4) is the reflected image of (5,2), find an equation for the line of reflection.
When I solved this problem, I know I didn't do it right because my line was the perpendicular bisector of those two points. (if they made a segment).
1 solutions

Answer 107674 by Nate(3495) About Me  on 2008-07-06 07:02:37 (Show Source):
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That should be right. Your line should be a perpendicular bisector to the segment formed by the two points.
m = (4 - 2) / (-1 - 5) = -1 / 3
Perpendicular slope = 3
w/ point ( (-1 + 5)/2 , (4 + 2)/2 ) or ( 2 , 3 )
y - y1 = m(x - x1)
y - 3 = 3(x - 2)
y - 3 = 3x - 6
y = 3x - 3


Geometry_proofs/147270: Given two parallel lines cut by a transversal, prove that a pair of alternate interior angles are congruent.
1 solutions

Answer 107673 by Nate(3495) About Me  on 2008-07-06 06:59:21 (Show Source):
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AB and CD are parallel segements cut by transversal EF with G at point of intersection of AB and EF and H at CD and EF:
angle EGB = angle GHD ~ corresponding angles
* angle EGB = angle AGH ~ vertical angles
angle AGH = angle GHD
Now, a repeat of the properties would show the other two interior angles are congruent.