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richard1234 answered: 5385 problems
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Equations/431771: Can you please explain how you would work this problem out I just don't understand the whol please excuse my dear aunt sally, but since multiplication goes before division why is it that on this equation you will have to divide before you do your multiplication. Im so confused....please help me understand this....
35(41-33)÷8-11+17
1 solutions
Answer 299568 by richard1234(5390) on 2011-04-05 23:03:28 (Show Source):
You can put this solution on YOUR website!Actually you have to multiply first before dividing:
35(41 - 33) ÷ 8 - 11 + 17
35(8) ÷ 8 - 11 + 17
35 - 11 + 17
= 41
Multiplying and dividing typically take equal precedence over each other, and in such a case you would simply go from left to right
(I checked WolframAlpha for its answer, it seemed as if it divided first, but both WolframAlpha and I got 41. This is mainly because the order of these operations usually doesn't matter, i.e.  ).
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Geometry_proofs/431252: I am having trouble with this proof
If given a line segment like ab
Construct a perpendicular line (i can do)
Prove that the line is perpendicular (i can't figure out)
I need a proof for a perpendicular bisector of a line.
Thank you!!
Mary 1 solutions
Answer 299535 by richard1234(5390) on 2011-04-05 21:01:10 (Show Source):
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Complex_Numbers/431744: Can you please tell me the answer to 5i to the fourth power? I think it is 625. My thought is, if "i" is involved, and a number is to an even power, then it is a positive number. If it is to an odd power, then it is a negative number. 1 solutions
Answer 299533 by richard1234(5390) on 2011-04-05 20:58:18 (Show Source):
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sets-and-operations/431739: Given these sets:
A = {3, 4, 5, 6, 7}
B = {6, 7, 8, 9}
C = {2, 4, 6, 8}
List the elements of this set
C ∩ (AUB)
Do not skip to the answer. Show your work 1 solutions
Answer 299522 by richard1234(5390) on 2011-04-05 20:43:22 (Show Source):
You can put this solution on YOUR website!A U B = {3, 4, 5, 6, 7, 8, 9} (simply take all elements in either A or B)
C ∩ (A U B) = {4, 6, 8} (these are the elements in both C and A U B)
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Complex_Numbers/431413: Why does ei*pi+1=0 other than the fact that my calculator says so, and so I believe it? 1 solutions
Answer 299519 by richard1234(5390) on 2011-04-05 20:41:07 (Show Source):
You can put this solution on YOUR website!Apparently it seems like the other tutor taught you this...:)
From Euler's formula,  . By substituting  you will obtain  ,  . Euler's formula itself is derived using the Maclaurin series for  , namely  (you will learn this sometime in calculus).
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Word_Problems_With_Coins/152564: how many ways to make change for one dollar using nickels, dimes and quarters 1 solutions
Answer 299461 by richard1234(5390) on 2011-04-05 16:12:32 (Show Source):
You can put this solution on YOUR website!You can compute the number of ways to make change for $1 using a bijection. We let n, d, q be the number of nickels, dimes, and quarters, and  , which implies  . Hence, this is equivalent to finding the number of ways to make 20 "cents" using one-, two-, and five-cent pieces.
Suppose we want to find the number of ways to make 20 cents *without* using a five cent piece.
Case 0: We wish to make 0 cents --> 1 way (just use no coins)
Case 1: We wish to make 1 cent --> 1 way 2*0 + 1*1
Case 2: We wish to make 2 cents --> 2 ways 2*1 + 1*0; 2*0 + 1*2
Case 3: We wish to make 3 cents --> 2 ways 2*1 + 1*1; 2*0 + 1*3
Case 4: We wish to make 4 cents --> 3 ways 2*2 + 1*0; 2*1 + 1*2, 2*0 + 1*4
Case 5: We wish to make 5 cents --> 3 ways 2*2 + 1*1, 2*1 + 1*3, 2*0 + 1*5
We can prove using either induction or modular arithmetic that the number of ways to make n cents in this way is  , where  denotes the floor value of x. We can evaluate this at n = 20 to get  , or 11.
Similarly, we can count the number of ways to obtain 20 cents using one five-cent piece. However, we can subtract off the five-cent piece and say that this is analogous to computing the number of ways to obtain 15 cents. Hence, this is equal to  .
For 10, 5, and 0 cents, we have  ,  and  . Therefore the total number of ways is 11 + 8 + 6 + 3 + 1 = 29 ways.
Note: the other tutor counted 293 ways, however this included pennies and half dollars, which was not stated in the question. To count the number of ways using pennies, nickels, dimes, and quarters, you can also use a bijection, but instead of counting the number of ways to obtain 20 cents, you evaluate at 20, 19, 18, ..., 0 since this will uniquely determine the number of pennies. We do the same with 15, 10, 5, and 0 to obtain sums:
Then, if you want half dollars involved, it is equal to  where  is the number of ways to make a dollar using i half dollars, equivalently, the number of ways to make 50 cents and 0 cents without half dollars (here you should get 293!).
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Trigonometry-basics/431469: Derive the half angle formula for sin( u/2 ) by following the steps below.
(a) Use the sum angle formula to write cos(2x) in terms of powers of sin(x)
and cos(x) .
(b) Use a trig identity to rewrite cos(2x) in terms of just powers of sin(x):
(c) Solve the formula in part (b) in terms of sin(x), and not a power of
sin(x).
(d) Substitute x = u/2 into the formula in part (c). 1 solutions
Answer 299459 by richard1234(5390) on 2011-04-05 15:43:05 (Show Source):
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Linear-equations/431524: Why should we clear fractions when solving linear equations and inequalities? Can you give me an example?
Why should we clear decimals when solving linear equations and inequalities? Can you give me an example. 1 solutions
Answer 299456 by richard1234(5390) on 2011-04-05 15:36:48 (Show Source):
You can put this solution on YOUR website!If you're given an equation or inequality such as  , it helps to clear the fraction or decimal since we are trying to find the value of  , not  .
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Equations/431282: Find the quadratic equation with integral coefficients having the given roots.
4 + 2i, 4 - 2i
Thanks!! 1 solutions
Answer 299375 by richard1234(5390) on 2011-04-05 00:10:20 (Show Source):
You can put this solution on YOUR website!The quadratic will have  and  as factors. Hence, the quadratic is equal to  (applying the difference of two squares)
Expanding and simplifying, this is equal to  .
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Radicals/431151: I am trying to simplify radical expressions.. It says Assume that the variables are positive. Write "nonreal" if the expression does not represent a real number. The problem is sqrt( 98 ). I know the answer is 7 sqrt ( 2 ) but I am not sure how I got that answer. How do I get from sqrt ( 98 ) to 7 sqrt (2) ?
Thanks! 1 solutions
Answer 299306 by richard1234(5390) on 2011-04-04 19:17:57 (Show Source):
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Trigonometry-basics/431008: how do i evaluate arccos(cos 7pi/2) using the properties of inverse functions? 1 solutions
Answer 299299 by richard1234(5390) on 2011-04-04 18:34:33 (Show Source):
You can put this solution on YOUR website!Arccosine and cosine are inverses of each other, so  would be equal to  . However, since the arccosine function restricts the range (since an infinite number of values are obtained), we say that this  . Depending on the context of the problem, either answer could be correct, or even some general answer in the form  .
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Quadratic_Equations/431169: What is x with x2-2x-13=0? And x2+12x-64=0? I've tried several times to find out what x is but neither of my solutions to these problems seem correct. 1 solutions
Answer 299298 by richard1234(5390) on 2011-04-04 18:31:48 (Show Source):
You can put this solution on YOUR website!Use the quadratic formula. The quadratic formula says that the roots of any quadratic equation in the form  (with a,b,c real) are  . From here, it's just simply identifying what a,b,c are and then substitution.
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Matrices-and-determiminant/431116: The vertices of a triangle are given below. Use a determinant and the vertices of the triangle to find the area of the triangle.
(-3,-7.5), (-1.5,6.5), (1.5,-5.5)
** By the way: I know that the answer is 30, I just don't understand how to get the answer. Thank you 1 solutions
Answer 299297 by richard1234(5390) on 2011-04-04 18:21:54 (Show Source):
You can put this solution on YOUR website!We have  where A =
| -3 -7.5 1 |
| -1.5 6.5 1 |
| 1.5 -5.5 1 | (3x3 matrix)
Here,
 ,
Therefore, the area is equal to 1/2 of 60, or 30.
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Evaluation_Word_Problems/431141: A restaurant is open from 2 pm to 2 am on Saturday and a maximum of 80 people are allowed inside. If f(t) is the number of people in the restaurant t hours after 2 pm on Saturday, what is a reasonable domain and range for y=f(t)?
Domain=
range= 1 solutions
Answer 299294 by richard1234(5390) on 2011-04-04 18:05:12 (Show Source):
You can put this solution on YOUR website!The restaurant is open up to 12 hours after the opening, so it is reasonable to say  . Also, between 0 and 80 people are allowed, so  .
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Triangles/430574: Is a triangle with side lengths of 3,4, and 5 and another triangle with side lengths of 6, 8, and 11 a counterexample of two similar right triangles? 1 solutions
Answer 299105 by richard1234(5390) on 2011-04-03 21:19:44 (Show Source):
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