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richard1234 answered: 5385 problems
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test/549517: 2x +6y
1 solutions

Answer 358526 by richard1234(5390) About Me  on 2011-12-25 23:07:29 (Show Source):
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Do you have a question?


Polynomials-and-rational-expressions/550122: Essay: Show all work. The area of a rectangular swimming pool is given by 2x^2 - 3x -9 ft^2. One side length of the pool is given by 2x + 3 feet. What is an algebraic expression for the other side length of the pool? Simplify this, and include correct units as part of your answer.
1 solutions

Answer 358525 by richard1234(5390) About Me  on 2011-12-25 23:06:40 (Show Source):
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The other side length is equal to



I'll let you do the polynomial division. You should get x - 3 as your result. The units are in feet (since we are looking for a length).


Reduction-of-unit-multipliers/550197: Is Celsius temperature a function of Fahrenheit temperature? explain.
please answer this...thanks
1 solutions

Answer 358524 by richard1234(5390) About Me  on 2011-12-25 23:05:12 (Show Source):
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Yes, we have

C = (5/9)(F - 32)

where F is the temperature in degrees Fahrenheit.


Functions/550132: How many positive integers n are such that the value of
the expression n^3 -14n^2 + 64n - 93 is a prime number?
1 solutions

Answer 358522 by richard1234(5390) About Me  on 2011-12-25 23:00:25 (Show Source):
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The expression factors to (n-3)(n^2 - 11n + 31). Since we want a prime number, either n-3 or n^2 - 11n + 31 must be equal to 1 (or -1). Solving for n, we obtain n = 2, 4, 5, or 6. Here are the values we obtain when we replace n into the given expression:

n = 2 --> -13
n = 4 --> 3
n = 5 --> 2
n = 6 --> 3

The values n = 4, 5, 6 produce prime numbers, so the answer is 3.


Equations/550195: i do not understand how to do one step equatons? can you explain to me how to do them?
1 solutions

Answer 358521 by richard1234(5390) About Me  on 2011-12-25 22:55:46 (Show Source):
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If you're trying to solve for x, do whatever operation is necessary to isolate x.

Note the phrase "one-step equation," should only take one step to solve, as opposed to computer algorithms which may take hundreds of steps.


Sequences-and-series/550089: prove that if k>1 then k^n→∞ an n→∞
there is a hint given. Hint:let k=1+t where t>0 and use the fact that (1+t)^n>1+nt
prove that if k is between 0 and 1 then k^n tends to 0 as n tends to infinity
1 solutions

Answer 358405 by richard1234(5390) About Me  on 2011-12-24 12:07:46 (Show Source):
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Given the hint, the problem becomes simple. Since 1 + nt approaches infinity as n approaches infinity, the LHS of the inequality is "bounded" by this expression, so the LHS must also approach infinity.


Permutations/549700: Directions: Form a group of 2 to 4 people. Select someone to record the group’s responses for
this activity. All members of the group should work cooperatively to answer the questions. If
your instructor asks for the results, each member of the group should be prepared to respond.
Minimum Wage The table shows the minimum wage for
three different years.
(a) Make a scatterplot of the data in the viewing rectangle
[1930, 2010, 10] by [0, 6, 1].
(b) Find a quadratic function given by
that models the data.
(c) Estimate the minimum wage in 1976 and compare
it to the actual value of $2.30.
(d) Estimate when the minimum wage was $1.00.
(e) If current trends continue, predict the minimum
wage in 2009. Compare it to the projected value of
$7.25.
1 solutions

Answer 358371 by richard1234(5390) About Me  on 2011-12-24 02:04:36 (Show Source):
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No data provided. Also, do you expect tutors on algebra.com to form groups of 2 to 4 people to answer these questions?


Triangles/549465: As the legs of a tripod are spread apart, which theorem guarantees that the angles between each pair of legs get larger?
1 solutions

Answer 358369 by richard1234(5390) About Me  on 2011-12-24 02:02:35 (Show Source):
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The law of cosines is sufficient. If d is the distance between two ends of the tripod (which is assumed to be increasing), and x is the length of each leg, then



where theta is the angle between two of the legs. It can be shown that if d increases, then theta also increases.


Linear-equations/549947: Explain why a point on the boundary line can not be used as a test point when grapging a linear inequality in two variables? provide an example.
1 solutions

Answer 358366 by richard1234(5390) About Me  on 2011-12-24 01:44:50 (Show Source):
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Points on the boundary line represent the equality cases, or where the two expressions you are comparing are equal. For example, if you know that x + y > 5 (note "strictly greater than 5") and you plug in (3,2), you get 5 > 5, which is not true. However if the inequality were x + y >= 5, (3,2) works.


Sequences-and-series/549996: Can a function be continuous at one value of x and discontinuous at all other
x E R? Explain your answer, giving proofs where appropriate.

1 solutions

Answer 358365 by richard1234(5390) About Me  on 2011-12-24 01:39:38 (Show Source):
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No. If f is continuous at x and only x, then for any x-values arbitrarily close to x, f must also be continuous (since continuity is defined using the limit as x approaches a fixed number), so we have a contradiction.


Miscellaneous_Word_Problems/548989: What is the least positive integral value of n for which (n - 12) divided by
(5n + 23) is a non-zero reducible fraction?

1 solutions

Answer 358234 by richard1234(5390) About Me  on 2011-12-23 02:20:48 (Show Source):
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Assume n > 12 so that the fraction is positive (1 through 11 don't work anyway). If the fraction is reducible for some n, then n-12 and 5n+23 must have a common factor p (other than 1). We can write this using modular arithmetic:

(mod p)

This implies (mod p), so (mod p). Hence, p = 83. Therefore, we can set n = 95, obtaining the fraction 83/498, or 1/6.



Sequences-and-series/549787: Give an example of a function that is continuous at all non-integer values but is discontinuous at all integer values. Prove the discontinuity property of your function.
1 solutions

Answer 358233 by richard1234(5390) About Me  on 2011-12-23 02:07:53 (Show Source):
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For example, let f(x) = 1 if x is not an integer, but f(x) = 0 if x is an integer (it is easier to write this function using piece-wise notation).

A function f(x) is not continuous if (but not only if)

. This is true because if a is an integer, the LHS equals 1 but the RHS equals 0. Therefore f is not continuous.


Volume/549854: determine the volume of the three-dimensional figure. When appropriate, round your answer to the nearest hundredth.a)12 in., b)30 in. ,c)30 in.2

1 solutions

Answer 358232 by richard1234(5390) About Me  on 2011-12-23 02:02:44 (Show Source):
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You didn't provide any information whatsoever of the figure. Also, none of the answer choices can be correct because the units for volume are (length)^3.


decimal-numbers/549955: Sum of three positive integers is 2^2011 + 1, and the product of two of them is 2^2011.how many values can the third integer take?
1 solutions

Answer 358230 by richard1234(5390) About Me  on 2011-12-23 01:52:27 (Show Source):
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Since the product of two of these integers is a power of 2, it follows that both integers are powers of 2. Hence these integers can be {1, 2^2011}, {2, 2^2010}, ..., {2^1005, 2^1006} (order doesn't matter). The two integers cannot be {1, 2^2011} since the third integer would be zero. However, each of the other ordered pairs produces a unique integer (e.g. subtract the sum of the two integers from 2^2011 + 1), so the number of values for the third integer is the number of ordered pairs in {2, 2^2010}, ..., {2^1005, 2^1006}, or 1004 integers.


Triangles/548749: The centroid of a triangle is ____?____ the circumcenter of a triangle.
A. Always
B. Sometimes
C. Never
1 solutions

Answer 358228 by richard1234(5390) About Me  on 2011-12-23 01:10:21 (Show Source):
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B, sometimes. The centroid is defined as the "center of mass" of the triangle, and the circumcenter is not defined this way. However, they can still be the same point, as in the case of an equilateral triangle.


Parallelograms/549542: Which of the following conditions or set of conditions is sufficient for a parallelogram to be a square?
1 solutions

Answer 358227 by richard1234(5390) About Me  on 2011-12-23 01:07:39 (Show Source):
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The only conditions required are that the parallelogram has four congruent sides (or equivalently, equal diagonals) and four right angles.


Average/549436: Hi, i am about to take my final exam and i need to pass this class. Can you tell me what grade i need to get on the test?
here are my scores-
Homework 8/9/11 Chapter 1 and 2 Review 50 50 / 50.0 = 100%
Homework 8/10/11 Chapter 3 review 25 25 / 25.0 = 100%
Homework 8/11/11 chapter 4 Review 25 25 / 25.0 = 100%
Homework 8/12/11 Chapter 5 review 25 25 / 25.0 = 100%
Homework 8/15/11 Chapter 6 review 25 25 / 25.0 = 100%
Quiz 8/15/11 quiz no. 1 50 50 / 50.0 = 100%
Homework 8/16/11 Pg. 401 1-19 10 10 / 10.0 = 100%
Homework 8/17/11 Pg. 408 17-34 10 10 / 10.0 = 100%
Homework 8/18/11 Pg. 414 9-29 odd 10 10 / 10.0 = 100%
Homework 8/25/11 Pg. 803 1-20 10 10 / 10.0 = 100%
Homework 8/26/11 Pg. 803 20-36 even 10 10 / 10.0 = 100%
Group Test 8/29/11 Chapter 7 GroupTest 100 100 / 260.0 = 38.46%
Homework 8/29/11 Pg. 803 9-16, 36-39 10 10 / 10.0 = 100%
Homework 8/30/11 Pg. 421 19-30 10 10 / 10.0 = 100%
Homework 8/31/11 Pg. 429 1-23,25,27,29 10 10 / 10.0 = 100%
Individual Test 8/31/11 Chapter 7 Individual Test 200 200 / 240.0 = 83.33%
Homework 9/1/11 Pg. 452 1-61 odd 15 15 / 20.0 = 75%
Homework 9/2/11 pg. 459 1-45 10 10 / 10.0 = 100%
Homework 9/6/11 Pg. 466 1-30 10 10 / 10.0 = 100%
Homework 9/6/11 Pg. 473 1-46 odd 10 10 / 10.0 = 100%
Group Test 9/7/11 Chapter 8 Group Test 150 150 / 200.0 = 75%
Homework 9/7/11 Pg. 494 1-32 10 10 / 10.0 = 100%
Homework 9/9/11 Pg. 494 1-32 5 5 / 10.0 = 50%
Homework 9/12/11 Pg. 507 1-43 odd 10 10 / 10.0 = 100%
Homework 9/13/11 Pg. 514 1-49 odd 5 5 / 10.0 = 50%
Individual Test 9/13/11 Chapter 8 Individual Test 183 183 / 200.0 = 91.5%
Homework 9/14/11 Pg. 521 1-19 5 5 / 10.0 = 50%
Homework 9/15/11 Pg. 521 21-43 5 5 / 10.0 = 50%
Homework 9/16/11 Pg. 529 1-19 5 5 / 10.0 = 50%
Homework 9/19/11 Pg. 536 1-15 5 5 / 10.0 = 50%
Homework 9/20/11 pg. 536 23-43 5 5 / 10.0 = 50%
Homework 9/21/11 Pg. 544 1-20 4 4 / 10.0 = 40%
Homework 9/22/11 pg. 544 21-30
0
0 / 10.0 = 0%
Homework 9/23/11 Review Chapter 9 10 10 / 20.0 = 50%
Group Test 9/26/11 Chapter 9 Group Test 125 125 / 145.0 = 86.21%
Homework 9/27/11 Review Chapter 9 10 10 / 10.0 = 100%
Individual Test 9/28/11 Chapter 9 Individual Test part 2 75 75 / 100.0 = 75%
Final exam 10/4/11 Final Exam Quarter 1 12 12 / 30.0 = 40%
Individual Test 10/4/11 chapter 9 individual Test 170 170 / 200.0 = 85%
Homework 10/5/11 pg. 580 16-38
0
0 / 10.0 = 0%
Homework 10/6/11 pg. 587 1-47 odd 5 5 / 10.0 = 50%
Homework 10/7/11 pg. 593 1-38 5 5 / 10.0 = 50%
Homework 10/7/11 Factoring Worksheet 9.3 -9.4
0
0 / 10.0 = 0%
Homework 10/11/11 pg. 600 18-43 5 5 / 10.0 = 50%
Homework 10/12/11 pg. 606 5-41 odd 5 5 / 10.0 = 50%
Homework 10/13/11 pg. 606 6-40 even 10 10 / 10.0 = 100%
Homework 10/14/11 pg. 614 15-47 odd 10 10 / 10.0 = 100%
Homework 10/17/11 pg. 614 16-46 even 10 10 / 10.0 = 100%
Homework 10/18/11 pg. 622 19-49 odd
0
0 / 10.0 = 0%
Homework 10/19/11 pg. 622 18-50 even 6 6 / 10.0 = 60%
Homework 10/20/11 pg. 629 21-50 10 10 / 10.0 = 100%
Homework 10/21/11 Chapter 10 Review
Group Test 10/24/11 Chapter 10 Group Test 210 210 / 250.0 = 84%
Homework 10/25/11 Review chapter 10
Individual Test 10/26/11 Chapter 10 Individual Test 60 60 / 210.0 = 28.57%
Homework 10/27/11 pg 646 17-39
0
0 / 10.0 = 0%
Homework 11/1/11 pg.658 #12-32 10 10 / 10.0 = 100%
Homework 11/2/11 pg.. 667 # 9-29 10 10 / 10.0 = 100%
Homework 11/3/11 Pg. 673 #12-26 10 10 / 10.0 = 100%
Homework 11/4/11 pg. 679 # 11-31 odd 5 5 / 10.0 = 50%
Homework 11/7/11 pg. 679 # 10-30 even 6 6 / 10.0 = 60%
Homework 11/8/11 pg. 687 # 1-22
0
0 / 10.0 = 0%
Homework 11/9/11 pg. 694 #1-34
0
0 / 10.0 = 0%
Group Test 11/10/11 Chapter 11 Group Test 36 36 / 160.0 = 22.5%
Homework 11/14/11 Review pg. 700 1-28
Individual Test 11/16/11 ch.11 individual test 36 36 / 210.0 = 17.14%
Homework 11/16/11 pg.712 # 1-17, 45-56
Homework 11/17/11 pg. 719 # 1-39 odd 6 6 / 10.0 = 60%
Homework 11/18/11 pg. 719 # 2-38 even 6 6 / 10.0 = 60%
Homework 11/29/11 pg. 725 # 5-47 odd 10 10 / 10.0 = 100%
Homework 11/30/11 pg. 725 #4-46 even
0
0 / 10.0 = 0%
Homework 12/5/11 pg.741 # 1-27 10 10 / 10.0 = 100%
Group Test 12/5/11 ch.12 group test 77 77 / 320.0 = 24.06%
Homework 12/6/11 Chapter 12 Review Pg. 766 1-22
Individual Test 12/7/11 ch.12 individual test
0
0 / 320.0 = 0%
Individual Test 12/7/11 Boardwork Chapter 12 Individual Test
Homework 12/8/11 Review Chapter 12
Score per Category
Category: Weight: Score:
Final exam 20% 40%
Group Test 5% 52.28%
Homework 15% 73.58%
Individual Test 40% 48.92%
Quarter Benchmark 10% -
Quiz 10% 100%
Click here for an explanation of weighting.

Grade Scale
A+ = 97% B- = 80% D = 63%
A = 93% C+ = 77% D- = 60%
A- = 90% C = 73% F = 0%
B+ = 87% C- = 70%
B = 83% D+ = 67%
1 solutions

Answer 358226 by richard1234(5390) About Me  on 2011-12-23 01:06:13 (Show Source):
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Get a 100% and you should be fine. If a 100% is not enough to pass, you're pretty much screwed, that's all I can say.

Seriously though, you shouldn't post all your grades here. If you really want to know what score you need on a final to pass, simply compute the weighted average of your overall grades (final, homework, test, quiz, etc.), letting your final grade be "x." Set this equal to the passing score (presumably 60%) and solve for x. Any score greater than or equal to x will allow you to pass.


Polynomials-and-rational-expressions/548823: Essay. List the terms, coefficients, and degree of the following polynomial: 5x^8 + 3x^6 – 2x + 4/5 or four fifths.
1 solutions

Answer 358225 by richard1234(5390) About Me  on 2011-12-23 01:00:54 (Show Source):
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Terms: 5x^8, 3x^6, -2x, 4/5
Coefficients: 5, 3, -2, 4/5
Degree: 8 (highest exponent of x)

I don't know why the problem requires an essay...


sets-and-operations/549952: given the universal set E={1,2,3,4,5,6,7,8,9,10}
what is the complement of {1,10}

1 solutions

Answer 358224 by richard1234(5390) About Me  on 2011-12-23 00:57:27 (Show Source):
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{2,3,4,5,6,7,8,9}


Quadratic_Equations/549912: select a natural number between 1 to 50. square the digits and add. repeat this process until you see a pattern.
What other numbers end with one?
What happen if you do the process to number 37?
What conclusion can you give?
1 solutions

Answer 358223 by richard1234(5390) About Me  on 2011-12-23 00:56:53 (Show Source):
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Suppose I choose 4. The numbers in the pattern are 16, 37, 58, 89, 145, 42, 20, 4, 16, and it repeats.

If the number 1 appears in the sequence, then the previous number must have been 1, 10, 100 or any power of 10. However, all succeeding terms in the sequence must be 1.

Doing the process to the number 37 yields the same sequence as if I did 4 (up to shifting terms).

We can conjecture that every number will eventually produce a periodic sequence. However we want to prove this. Given a sequence a_1, a_2, ... we want to show that a_i = a_j for some distinct i,j (this will produce a periodic sequence). Since it is tricky to establish an explicit formula for a_i, we can instead show that a_i attains a maximum value. Since your sequence can be arbitrarily long, then by Pigeonhole principle, two numbers in the sequence must be the same, and hence the sequence is periodic. I'll leave it to you to prove that a_i attains a maximum value...


Sequences-and-series/549782: Given a geometric series with first term a > 0 and common ration r > 0 prove that a finite “sum to infinity” exists if and only if r < 1 and show that in this case the sum to infinity is .
1 solutions

Answer 358222 by richard1234(5390) About Me  on 2011-12-23 00:44:56 (Show Source):
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We prove that a convergent sum exists by evaluating the limit as the number of terms approaches infinity:





Since r^(n+1) tends to zero, the sum converges to 1/(1-r). However, this only holds when |r| < 1. Otherwise, the limit diverges.


Equations/549950: 2x + 3y =1
-2x + y =11
1 solutions

Answer 358220 by richard1234(5390) About Me  on 2011-12-23 00:38:26 (Show Source):
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Add both equations to get 4y = 12; this implies y = 3. Substitute y with 3 into either equation to obtain x = -4.


Quadratic_Equations/548600: The solutions of x^3 – 2x^2 + 3x + 4 = 0 are a, b, and c. what is the numerical value of (a + b)(a + c)(b + c) ?

1 solutions

Answer 358053 by richard1234(5390) About Me  on 2011-12-22 11:37:11 (Show Source):
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By Vieta's formulas, a+b+c = 2. Hence we are evaluating (2-c)(2-b)(2-a). We could expand this entire expression (since we are guaranteed to obtain useful cyclic sums:





However, we have a+b+c = 2, ab+ac+bc = 3, abc = 4 (you can verify these by expanding (x-a)(x-b)(x-c) and equating like terms). Hence, the expression we want is equal to



Triangles/548650: in an isocles triangle, without any measurements, i have to find the each individual angle, what is a formula i could use?
1 solutions

Answer 358048 by richard1234(5390) About Me  on 2011-12-22 11:31:11 (Show Source):
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You need to know at least one of the angles (or some side lengths), and use the constraint that the sum of the angles is 180.


Polynomials-and-rational-expressions/549780: Short Answer. The length of the side of a rectangular desk is given by x - 4y cm. The length of the front is given by x + 4y cm. What is an algebraic expression for the area of the top of the rectangular desk? Include correct units as part of your answer.
1 solutions

Answer 358045 by richard1234(5390) About Me  on 2011-12-22 11:28:58 (Show Source):
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The area is (x-4y)(x+4y) = x^2 - 16y^2 (cm^2).


Sequences-and-series/549775: Let k > 0 be a constant and consider the important sequence {kn}. It’s behaviour as n tends to infinity will depend on the value of k.
(i) State the behaviour of the sequence as n tends to infinity when k = 1 and when k = 0.
(ii) Prove that if k > 1 then kn tends to infinity as n teds to infinity
(hint: let k = 1 + t where t > 0 and use the fact that (1 + t)n > 1 + nt.
(iii) Prove that if 0 < k < 1 then kn tends to 0 as n tends to infinity .

1 solutions

Answer 358044 by richard1234(5390) About Me  on 2011-12-22 11:18:18 (Show Source):
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Is your sequence kn or k^n? You typed kn, which is interpreted as "k times n" but in question iii) but you implied that the limit as n goes to infinity of kn/k^n (where 0 < k < 1) is zero.

Either way, you can use limits or any other technique. If you mean k^n, part i) is simple, because 1^n is always 1 and 0^n is always 0.

For part ii), we can actually prove it by assuming that on the other hand k^n converges to some number X. If this is so, then k(k^n) must also converge (to kX). However, k(k^n) is equivalent to k^n (since we are evaluating where n approaches infinity) so kX = X. This implies X = 0 (since k is not 1), contradiction. Hence k^n diverges.

For part iii), assume on the other hand it diverges. We have |k(k^n)| < |k^n| (since |k| < 1). This is also a contradiction because we assumed it diverges, so it converges. By the same argument in ii), it converges to 0.


Divisibility_and_Prime_Numbers/549506: What is the remainder when 2^1024 + 5^1024 +1 is divided by 9?
1 solutions

Answer 358040 by richard1234(5390) About Me  on 2011-12-22 11:03:37 (Show Source):
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Several ways to do this. One way is to that

, and that

(modulo 9).

Similarly,

(modulo 9).

Hence the sum is equivalent to 7 + 4 + 1 = 12 = 3 (modulo 9), so the remainder is 3.


Geometry_proofs/548583: please give me a short definiton of prrof that referrs to geometry Please
1 solutions

Answer 357117 by richard1234(5390) About Me  on 2011-12-18 10:13:36 (Show Source):
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A proof is simply a set of statements that proves why a certain theorem or statement is true.


Rectangles/548607: what is the perimeter of a triangle whose length is 7 feet and whose width is 6 feet
1 solutions

Answer 357115 by richard1234(5390) About Me  on 2011-12-18 10:10:09 (Show Source):
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A triangle? Or rectangle?


Polynomials-and-rational-expressions/547904: Take a number (except 1). Square that number and then subtract 1. Divide by one less than your original number. Now subtract your original number. How does this number game work? How did the number game use the skill of simplifying rational expressions?
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Answer 357057 by richard1234(5390) About Me  on 2011-12-17 22:23:23 (Show Source):
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You'll always get 1 because



Exponents-negative-and-fractional/548528: Essay; show all work. Consider that the age, x, of a unicorn in human equivalent years can be given by the formula f(x) = - 0.011718x4 + 0.187326x3 – 1.3367x2 + 12.46x + 2.914. When a unicorn is 2.5 years old, what is its age in human equivalent years? What about when it is 12 years old?
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Answer 357056 by richard1234(5390) About Me  on 2011-12-17 22:20:11 (Show Source):
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Replace x with 2.5, then simplify to find f(2.5). Do the same with f(12).