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Divisibility_and_Prime_Numbers/364481: How many integers from - 3000 to 3000 inclusive are divisible by 3 ?
1 solutions

Answer 259887 by Fombitz(13828) About Me  on 2010-11-01 10:38:17 (Show Source):
You can put this solution on YOUR website!
Count from 0 to 3000 for numbers divisible by 3 and then double that number.
Starting from 3 to 3000 by 3's which is the same as counting from 1 to 1000 by 1's.
N=1000
Double it for -3 to -3000.
N=2000 numbers.


Polynomials-and-rational-expressions/364474: g(x)=1/x^6
prove g is not one to one using the defintion of a one to one function.
1 solutions

Answer 259885 by Fombitz(13828) About Me  on 2010-11-01 10:15:08 (Show Source):
You can put this solution on YOUR website!
By definition,
g%28a%29=g%28b%29 only if a=b
.
.
g%281%29=1
g%28-1%29=1
So g%28x%29 is not one-to-one.


Probability-and-statistics/364479: 1. If the random variable z is the standard normal score, is it true that P(-3 < z < 3) > 1? Why or why not?

2. Givent a binomial distribution with n = 29 and p = 0.83, would the normal distribution provide a reasonable approximation? Why or why not?

3. Find the area under the standard normal curve for the following: a). P(z < -0.25) b). P(0.55 < z < 0) c.) P(-1.91 < z < 1.06)
1 solutions

Answer 259884 by Fombitz(13828) About Me  on 2010-11-01 10:11:25 (Show Source):
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1) P%28z%29=int%28p%28x%29%2Cdx%2C-infinity%2Cz%29
int%28p%28z%29%2Cdz%2C-infinity%2Cinfinity%29=1
So P can never be greater than 1.
.
.
2)
The binomial distribution is approximated by a normal distribution for any fixed p(even if p is small) as n is taken to infinity.
.
.
3) P%28z%3C0.25%29=P%280.25%29
.
.
+P%280.55+%3C+z+%3C+0%29=P%280.55%29-P%280%29
P%280.55+%3C+z+%3C+0%29=P%280.55%29-0.5
.
.
+P%28-1.91+%3C+z+%3C+1.06%29=P%281.06%29-P%28-1.91%29


Linear-equations/364387: Perform a long division:
2u^3 - 13 u^2 -8u + 7 /u - 7
1 solutions

Answer 259883 by Fombitz(13828) About Me  on 2010-11-01 10:05:03 (Show Source):
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        2u^2 + u - 1
       __________________________
u - 7 | 2u^3 - 13u^2 - 8u +  7
      -(2u^3 - 14u^2)
       -------------------
                 u^2 - 8u
              - (u^2 - 7u)
                --------------
                        -u + 7 
                      -(-u + 7)
                       ---------
                             0

highlight%28%282u%5E3-13u%5E2-8u+%2B+7%29%2F%28u-7%29=%282u%5E2%2Bu-1%29%29


Length-and-distance/364466: Hi All,
Having difficulty with this particular problem on a task sheet, any help would be greatly appreciated.
Given a=i+3j-k and b=2i+j-k, find a.b and the cosine of the angle Theta between the vectors
b) Given a= 3i+j-2k and b= -6i-2j+4k find a.b and the angle theta between vectors
Finaly c) For what value of alpha will the vectors a+5i+2j+3k and b=2i+alphaj+alphak be perpendicular?
Many thanks in advance for any help.
Mike
1 solutions

Answer 259882 by Fombitz(13828) About Me  on 2010-11-01 09:56:25 (Show Source):
You can put this solution on YOUR website!
b) Use the dot product.
a=(3,1,-2)
b=(-6,-2,4)
a%2Ab=3%28-6%29%2B1%28-2%29%2B%28-2%29%284%29=-18-2-8=-28
a%2Ab=abs%28a%29abs%28b%29cos%28theta%29
abs%28a%29=sqrt%283%5E2%2B1%5E2%2B%28-2%29%5E2%29=sqrt%289%2B1%2B4%29=sqrt%2814%29

-28=sqrt%2814%29%282%2Asqrt%2814%29%29cos%28theta%29
cos%28theta%29=-28%2F%282%2A14%29
cos%28theta%29=-1
highlight%28theta=180%29
.
.
.
c)
Perpendicular means theta=90.
cos%2890%29=0
So then a%2Ab=0
a=(5,2,3)
b=(2,alpha,alpha)
a%2Ab=5%2A2%2B2%2Aalpha%2B3%2Aalpha=10%2B5%2Aalpha
10%2B5%2Aalpha=0
5%2Aalpha=-10
highlight%28alpha=-2%29


Mixture_Word_Problems/364472: How many gallons of antifreeze do I need to keep 450 gallons of water from freezing?
1 solutions

Answer 259878 by Fombitz(13828) About Me  on 2010-11-01 09:42:16 (Show Source):
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Depends on the type of antifreeze (alcohol, ethylene glycol, etc.). However you should check with the manufacturer of the specific brand to see the mix for the temperature you're protecting against.



Rational-functions/364470: 1) Given the function f:x=6X-(2/X), X>0, Find:
a) F-1(inverse)
b) f-1(-1)
c) f-1(-4)
1 solutions

Answer 259877 by Fombitz(13828) About Me  on 2010-11-01 09:39:33 (Show Source):
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y=6x-2%2Fx
x=6y-2%2Fy
xy=6y%5E2-2
6y%5E2-xy=2
Complete the square in y.
6%28y%5E2-%28x%2F6%29y%29=2
6%28y%5E2-%28x%2F6%29y%2B%28x%5E2%2F144%29%29=2%2B6%28x%5E2%2F144%29
6%28y-x%2F12%29%5E2=2%2Bx%5E2%2F24
%28y-x%2F12%29%5E2=1%2F3%2Bx%5E2%2F144
y-x%2F12=0+%2B-+sqrt%281%2F3%2Bx%5E2%2F144%29
y=x%2F12+%2B-+sqrt%281%2F3%2Bx%5E2%2F144%29
highlight%28f%5E%28-1%29%28x%29=x%2F12+%2B-+sqrt%281%2F3%2Bx%5E2%2F144%29%29
.
.
.
Use the inverse function and substitute x=-1 and x=-4 and solve for f%5E%28-1%29%28x%29.


Polynomials-and-rational-expressions/364378: Find all of the real solutions of the polynomial equation.
2x^4 + 7x^3 - 26x^2 + 23x -6 = 0

1 solutions

Answer 259874 by Fombitz(13828) About Me  on 2010-11-01 09:31:22 (Show Source):
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graph%28300%2C300%2C-1%2C2%2C-2%2C2%2C2x%5E4+%2B+7x%5E3-26x%5E2+%2B+23x-6%29
Looks like x=1%2F2 and x=1 are possible zeros.
Verify they are by pluggin them into the equation to make sure it's satisfied.
The other two solutions are complex.


real-numbers/364359: Factor out the greatest common factor.
3x^2y^5+18x^2y^4
1 solutions

Answer 259873 by Fombitz(13828) About Me  on 2010-11-01 09:28:30 (Show Source):


Graphs/364341: graph the inequality: x-y>-5
1 solutions

Answer 259872 by Fombitz(13828) About Me  on 2010-11-01 09:27:22 (Show Source):
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Graph the line, x-y=-5
y=x%2B5
.
.
.
graph%28300%2C300%2C-7%2C3%2C-5%2C5%2Cx%2B5%29
Now choose a point not on the line.
Test the inequality.
If the inequality is satisfied, shade the region containing the point.
If not, shade the region not containing the point.
Choose (0,0) for convenience.
x-y%3E-5
0-0%3E-5
0%3E-5
True, shade the region containing (0,0).
.
.
Solved by pluggable solver: Plot Any Inequality
Graphing function x-y%3E-5:

graph%28+300%2C+300%2C+-7%2C+3%2C+-5%2C+5%2C+x-y%3E-5+%29



Systems-of-equations/364355: what are the steps that you go through using substitution to answer systems of quadratics?
2y^2+x^2=4
y+x=3
1 solutions

Answer 259870 by Fombitz(13828) About Me  on 2010-11-01 09:21:49 (Show Source):
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DUPLICATE See Systems-of-equations/364352:


Percentage-and-ratio-word-problems/364421: At a picnic, the ratio of adults to children was 7 : 4.There were 15 more adults
than children. How many people were at the picnic?
1 solutions

Answer 259869 by Fombitz(13828) About Me  on 2010-11-01 09:19:55 (Show Source):
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Let A be the number of adults, C children.
1.A%2FC=7%2F4
2.A=15%2BC
From eq. 1,
4A=7C
From eq. 2,
4A=60%2B4C
Substitute from eq. 1,
7C=60%2B4C
3C=60
highlight%28C=20%29
Then from eq. 2,
A=15%2B20
highlight%28A=35%29


Linear_Equations_And_Systems_Word_Problems/364463: One angle of a triangle is three times as large as another. The measure of the third angle is 40 degrees more than that of the smallest angle. Find the measure of each angle.
1 solutions

Answer 259868 by Fombitz(13828) About Me  on 2010-11-01 09:17:20 (Show Source):
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Let A, B, and C be the angle from smallest to largest.
By defintion,
A%2BB%2BC=180
.
.
B=3A
C=40%2BA
.
.
.
Substituting,
A%2B3A%2B40%2BA=180
5A%2B40=180
5A=140
highlight%28A=28%29degrees
Then
B=3%2828%29
highlight%28B=84%29degrees
And
C=40%2B28
highlight%28C=68%29degrees


Systems-of-equations/364352: what are the steps that you go through using substitution to answer systems od quadratics?
2y^2+x^2=4
y+x=3
1 solutions

Answer 259866 by Fombitz(13828) About Me  on 2010-11-01 09:13:35 (Show Source):
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One's a ellipse, one's a line.
1. 2y%5E2%2Bx%5E2=4
2.y%2Bx=3
From eq. 2,
y=3-x
Substitute into eq. 1,
2%283-x%29%5E2%2Bx%5E2=4
2%289-6x%2Bx%5E2%29%2Bx%5E2=4
18-12x%2B2x%5E2%2Bx%5E2=4
3x%5E2-12x%2B18=4
3x%5E2-12x%2B14=0
There are no real solutions which means the line and the ellipse do not intersect.
.
.
.



Rational-functions/364459: 1) Givem the function F:X=6X-2/X, X>0,find:
a) F-1(inverse)
b) f-1(-1)
c) f-1(-4)
1 solutions

Answer 259863 by Fombitz(13828) About Me  on 2010-11-01 09:05:34 (Show Source):
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y=%286x-2%29%2Fx
Interchange x and y and solve for y.
The new y will be the inverse of the original function.
highlight_green%28x%29=6%2Ahighlight_green%28y%29-2%29%2Fhighlight_green%28y%29
xy=6y-2
xy-6y=-2
y%28x-6%29=-2
y=-2%2F%28x-6%29
highlight%28+F%5E%28-1%29%28x%29=2%2F%286-x%29%29
.
.
F%5E%28-1%29%28-1%29=2%2F%286-%28-1%29%29
highlight%28+F%5E%28-1%29%28-1%29=2%2F7%29
.
.
F%5E%28-1%29%28-4%29=2%2F%286-%28-4%29%29
F%5E%28-1%29%28-4%29=2%2F10
highlight%28+F%5E%28-1%29%28-4%29=1%2F5%29


Length-and-distance/364408: Find each of the following:
a.) 113degrees 57minutes + 18.4degrees

b.) 0.75degrees in minutes and seconds
1 solutions

Answer 259861 by Fombitz(13828) About Me  on 2010-11-01 08:59:43 (Show Source):
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1+degree = 60 minutes.
1 minute = 60 seconds.
.
.
.
0.4 degrees=%280.4%29%2860%29=24 minutes.
113d,57m + 18.4d=113d,57m+18d,24m
113d,57m + 18.4d=170d,81m
113d,57m + 18.4d=171d,21m
.
.
.
0.75d=0.75%2860%29=45m
0.75d=45m,0s


Inequalities/364420: Describe the solution set for the inequality | 3x - 5 | + 4 < 2 if x is an element of the set of integers
1 solutions

Answer 259859 by Fombitz(13828) About Me  on 2010-11-01 08:55:02 (Show Source):
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abs%283x-5%29%2B4%3C2
abs%283x-5%29%3C-2
No absolute value function output can provide a value less than zero.
There is no solution.


Matrices-and-determiminant/364426: Solve the matrix equation
-2x+3■(2&-8@-4&2)=■(4&-6@2&-8)
I am not sure how to type matrices in here.
Please help, I am trying to help my son with his algebra and neither one of us understands how to do this. Could you please explain in step by step instructions. Thank You.
1 solutions

Answer 259858 by Fombitz(13828) About Me  on 2010-11-01 08:53:33 (Show Source):
You can put this solution on YOUR website!
You can list them in order, like,
[A] is a 2x2 matrix [A]=(1 2 3 4) for [A]=%28matrix%282%2C2%2C1%2C2%2C3%2C4%29%29
[B] is a 3x3 matrix [B]=(9 8 7 6 5 4 3 2 1) for [B]=%28matrix%283%2C3%2C9%2C8%2C7%2C6%2C5%2C4%2C3%2C2%2C1%29%29
[C] is a 3x1 matrix [C]=(x y z) for [C]=%28matrix%283%2C1%2Cx%2Cy%2Cz%29%29
Then solve,
4[B][C]-12[C]


Probability-and-statistics/364427: Verify that Σx = 1.965, Σx2 = 0.5572, Σy = 30.5, Σy2 = 152.23, and Σxy = 8.8615.
Compute r. (Round your answer to three decimal places.)

1 solutions

Answer 259855 by Fombitz(13828) About Me  on 2010-11-01 08:49:49 (Show Source):
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No data provided.
Please re-post.


Probability-and-statistics/364428: For the least-squares line y^ = 2 − 2x, what is the value of the slope?
When x changes by 1 unit, by how much does y^ change?
Answer: I know y^ decreases but I cannot figure out how much.
1 solutions

Answer 259854 by Fombitz(13828) About Me  on 2010-11-01 08:49:18 (Show Source):
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The line is in slope intercept form, y=mx%2Bb where m is the slope.
Comparing,
m=-2


Probability-and-statistics/364429: Find the sums Σx, Σy, Σx2, Σy2, Σxy and and the value of the sample correlation coefficient r.
1 solutions

Answer 259852 by Fombitz(13828) About Me  on 2010-11-01 08:48:22 (Show Source):
You can put this solution on YOUR website!
No data provided.
Please re-post.


percentage/364431: How much pure alcohal should be added to 400 ml of 15% strength to make its strength 32%?
1 solutions

Answer 259851 by Fombitz(13828) About Me  on 2010-11-01 08:47:51 (Show Source):
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Pure alcohol is 100% strength.
Let X be the amount of pure alcohol added.
100X%2B15%28400%29=32%28X%2B400%29
100X%2B6000=32X%2B12800
68X=6800
highlight%28X=100%29ml


Exponential-and-logarithmic-functions/364455: Hi, I'm looking for some serious help. If anyone could help me, by showing all the steps you utilized to get the answer, I would greatly appreciate it.
Section 12.1, #5, pg 826
Directions: Approximate each number using a calculator. Round your answer to three decimal places.
4^(-1.5)


1 solutions

Answer 259849 by Fombitz(13828) About Me  on 2010-11-01 08:45:48 (Show Source):
You can put this solution on YOUR website!
Using a calculator or not using a calculator?



Linear-systems/364435: Find the slope-intercept equation of the line parallel to the line 12x + 3y = 15 and containing the point (–1, 7). Explain and show work.
1 solutions

Answer 259848 by Fombitz(13828) About Me  on 2010-11-01 08:43:14 (Show Source):
You can put this solution on YOUR website!
First find the slope of the first line by converting to slope-intercept form, y=mx%2Bb.
12x%2B3y=15
3y=-12x%2B15
y=-4x%2B5
m=-4
Parallel lines have identical slopes,
m%5B1%5D=m%5B2%5D=-4
.
.
y=-4x%2Bb
Use the point (-1,7) to solve for b.
7=-4%28-1%29%2Bb
b=3
.
.
.
highlight_green%28y=-4x%2B3%29
.
.
.


Linear-systems/364436: Given x=
x+7
_______
x^(2)-9
determine the domain.
A. All real numbers except –3 and 3
B. All real numbers except –7 and 3
C. All real numbers except –7, –3, and 3
D. All real numbers except 0

1 solutions

Answer 259847 by Fombitz(13828) About Me  on 2010-11-01 08:39:39 (Show Source):
You can put this solution on YOUR website!
I think you mean y=%28x%2B7%29%2F%28x%5E2-9%29=%28x%2B7%29%2F%28%28x-3%29%28x%2B3%29%29
The domain is all numbers except those that make the denominator equal zero since division by zero is undefined.
A) All except x=3 and x=-3.


Inequalities/364449: The inequality x^2 - 2x + 1 ≤ 0 has
A) no solutions
B) a set of solutions
C) 1 solution only
D) 2 solutions only
E) 3 solutions only
1 solutions

Answer 259845 by Fombitz(13828) About Me  on 2010-11-01 08:38:09 (Show Source):
You can put this solution on YOUR website!
graph%28300%2C300%2C-3%2C3%2C-3%2C3%2C0%2Cx%5E2-2x%2B1%29
.
.
.
x%5E2-2x%2B1%3C=0
%28x-1%29%5E2%3C=0
The square of a number can never be less than zero.
The equation can only be satisfied when x-1=0 or x=1.
C) One solution.


Linear-systems/364439: The points (2, 5) and (4, –1) are endpoints of the diameter of a circle.
(a) State the center of the circle.
(b) Find the length of the radius of the circle. (Note that this is a distance.) Show work.
(c) State the equation of the circle (in standard form). Note that you know the center and the radius from the previous parts.


1 solutions

Answer 259844 by Fombitz(13828) About Me  on 2010-11-01 08:34:33 (Show Source):
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a)Use the midpoint formula,
x%5Bm%5D=%28x%5B1%5D%2Bx%5B2%5D%29%2F2=%282%2B4%29%2F2
y%5Bm%5D=%28y%5B1%5D%2By%5B2%5D%29%2F2=%285%2B%28-1%29%29%2F2
.
.
.
b) Use the distance formula,
D%5E2=%28x%5B2%5D-x%5B1%5D%29%5E2%2B%28y%5B2%5D-y%5B1%5D%29%5E2
D%5E2=%285-2%29%5E2%2B%28-1-4%29%5E2
D=sqrt%289%2B25%29
.
.
.
c) Use the equation of a circle centered at (h,k) with radius R.
%28x-h%29%5E2%2B%28y-k%29%5E2=R%5E2
%28x-x%5Bm%5D%29%5E2%2B%28y-y%5Bm%5D%29%5E2=%28D%2F2%29%5E2
Expand the x and y terms to get to standard form.


Polynomials-and-rational-expressions/364441: Divide and Simplify.
x^2-36/x ÷ x-6/x+8
1 solutions

Answer 259843 by Fombitz(13828) About Me  on 2010-11-01 08:30:54 (Show Source):


Probability-and-statistics/364443: probability of Ann passing her math test is 90%. The probability she passes her English test is 80%. The probability she passes her Chemistry test is 70%. What is the probability she passes all three tests?
1 solutions

Answer 259841 by Fombitz(13828) About Me  on 2010-11-01 08:28:20 (Show Source):


Functions/364447: find the domain: f(x)=5x*e^(4x)
1 solutions

Answer 259840 by Fombitz(13828) About Me  on 2010-11-01 08:27:44 (Show Source):
You can put this solution on YOUR website!
There are no restrictions on x.
Domain:(-infinity,infinity)


Probability-and-statistics/364333: Automobiles arrive at the Elkhart exit of the Indiana Toll Road at the rate of two per minute. The distribution of arrivals approximates a Poisson distribution.
1. What is the probability that no automobiles arrive in a particular minute?
2. What is the probability that at least one automobile arrives during a particular minute?

1 solutions

Answer 259769 by Fombitz(13828) About Me  on 2010-10-31 21:08:12 (Show Source):