Monday
March 30, 2015

Posts by damon


Total # Posts: 20,745

Calculus - all the same question
If you can follow the one I did, you can do the rest.
March 30, 2015

Calculus
dC/dx = 100 - .2 x at x = 35 dC/dx = 100 - 7 = 93 dollars per club at a level of 35 clubs by the way total C for 35 clubs = 3877.5 or about an average of 111 dollars per club
March 30, 2015

Chemistry
one C per molecule? 6.02 * 10^23 molecules per mol 2.46 * 10^25 molecules *(1/6.02*10^23) = 40.9 mols How many grams? 40.9 * (12 + 4(35.5) ) what volume? grams / 2.71 g/mL
March 29, 2015

Differential Calculus
radius of circle = r side of square = s 10 = 4 s + 2 pi r so s = 2.5 - .5 pi r A = pi r^2 + s^2 or A = pi r^2 + 6.25 - 2.5 pi r + .25 pi^2 r^2 A = (.25 pi +1)pi r^2 -2.5 pi r + 6.25 I am going to use calculus, you can complete the square to find vertex of parabola dA/dr = 0 ...
March 29, 2015

Geometry
I used 400, use 500
March 29, 2015

Geometry
2 h + 2 w = 400 h + w = 200 w + 40 + w = 200 2 w = 160 w = 80 h = 120
March 29, 2015

Civics to Ms.Sue
Ms Sue is completely correct. There were presidents under the Articles.
March 27, 2015

Civics to Ms.Sue
It did not allow for a Department of Commerce :)
March 27, 2015

Civics to Ms.Sue
Well, the Articles of Confederation allowed for a president.
March 27, 2015

Algebra 1
0 = -0.04x^2+1.3x+56 or 0 = 0.04x^2 - 1.3x - 56 solve quadratic
March 27, 2015

us history
Now why would a state stay in the Union even if some of its residents had slaves? Maybe some of them did not have slaves and disagreed with the others?
March 27, 2015

us history
I do not think it is b or d
March 27, 2015

Algebra 1
.04 x^2 - 8.3 x - 4.3 = 0 http://www.webgraphing.com/quadraticequation_quadraticformula.jsp#
March 27, 2015

Algebra 1
y = x (-.04 x + 8.3) when is y = 0 at the start of course but also when .04 x = 8.3 or x = 207.5 meters I think you left a significant figure out :)
March 27, 2015

Algebra
y = k/x 300 = k /4 so k = 1200 y = 1200/150 y = 8
March 27, 2015

Algebra
I bet you mean [ f(x) - f(a) ] / (x-a) Parentheses are VITAL ! f(a) = -2 a^2 + 5 a - 1 so [ -2(x^2-a^2) +5(x-a) -1+1 ]/(x-a) = [-2(x-a)(x+a) + 5(x-a) ]/(x-a) = -2(x+a)+5 Note for future calculus purposes that the limit of this as a approaches a this becomes -4 x + 5
March 27, 2015

us history
I do physics actually. I just happened to know this.
March 27, 2015

us history
Jim Crow laws, C is right.
March 27, 2015

Algebra
distance = pi D in feet = pi * 64 * (1 mile/5280 ft) time = 25 s (1 h /3600 s) divide the distance in miles by the time in hours
March 27, 2015

algebra
y dy = x dx y^2/2 = x^2/2 + c or y^2 = x^2 + c (-3)^2 = 0 + c so c = 9 y^2 = x^2 + 9 y = +/- (x^2+9)^(1/2) since only y = -3 is given I think your answer correct
March 27, 2015

math
AB^2 = 64 + 4 = 68 BC^2 = 9 + 9 = 18 AC^2 = 25 + 25 = 50 Note that 68 = 50 + 18 therefore a right triangle
March 27, 2015

physics
F = m A F = (10.45)(2.5)
March 27, 2015

Economics
10 years 10.3 = 1.9 (1+r)^10 10 log(1+r) = log(5.42) log(1+r) = .0734 1+r = 1.184 so 18.4 percent per year
March 27, 2015

math
http://davidmlane.com/hyperstat/z_table.html
March 27, 2015

Pre-Calculus
Because she used parentheses.
March 26, 2015

Math
a) .15 * 15 = 2.25 NOT 1 c) correct e) corrtect
March 26, 2015

Math
b) CORRECT c) .045 * 1000 = 45 CORRECT ! d) NO way, you really feel 45 m is almost half a kilometer? e) 4500 / 1000 = 4.5 meters!
March 26, 2015

Math
old area = 400 ft^2 perimeter = 20+80 = 100 so 4 s = 100 s = 25 s^2 = area = 625 625 - 400 = ???
March 26, 2015

Math
4 = 1 + 3 or 2 + 2 or 3 + 1 so 3 out of 36 which is 1/12
March 26, 2015

Geometry
L w = 2 2 L * 3 w = 6*2 = 12
March 26, 2015

mathematical physics
we need the component of force in the direction of motion. F dot vector tangent to motion tangent to motion is velocity vector dX = Vdt if X is position vector and V is velocity vector X = t i + t j + t k V = dX/dt = i + j + k F dot V = y^2z^3 + 2 xyz^3 + 3x y^2 z^2 = t^5 + 2 ...
March 23, 2015

math
Thank you Reiny. Indeed we had quite a time getting ready for the first day of sailing practice.
March 23, 2015

math - binomial dist, no time to do it
use binomial distribution. I have to go clean seagull poop and snow off high school sailing floats, will check back this afternoon to see if you got it.
March 23, 2015

Algebra 1
y = x straight line through origin slope of one. y = 1 x + 0
March 22, 2015

CHEMISTRY
P V = n R T V same n same R same T same so partial pressure of each is 1/2 atm.
March 22, 2015

Algebra
http://www.jiskha.com/display.cgi?id=1427052839
March 22, 2015

Algebra
No problem :)
March 22, 2015

Algebra
I wrote (3 y - ) (y + ) and tried factors soon saw needed (3 y + ) (y - ) then fooled with 3 and 4 and then 6 and 2 until it worked
March 22, 2015

Algebra
Sure, fooled around with factors of 12 3 and 4 did not work, 1 and 12 did not work, so tried 6 and 2
March 22, 2015

Algebra
You are welcome.
March 22, 2015

Algebra
(3 y + 2)(y - 6)
March 22, 2015

math
combinations of 15 ten at a time n = 15 r = 10 C(n,r) = n!/[ r!(n-r)! ] = 15! /[ 10! (5!) ] = 15*14*13*12*11 /(5*4*3*2) = 15/15 * 14/2 * 13 * 12/4 * 11 = 7 * 13 * 3 * 11 = 3003
March 22, 2015

algebra
6 by 6 matrix of possibilities but 5 and 1 is the same as 1 and 5 for example so really not 36 possible results but only the diagonal and those below (or those above) so 6 + 5 + 4 + 3 + 2 + 1 = 21 possible combinations of which 3 add to 6 (they are (3,3)(2,4)(5,1) ) so THREE ...
March 22, 2015

College Math
new length = 36 - 2x new width = 24 - 2 x so V = (36-2x)(24-2x)x = 864x - 120 x^2 + 4 x^3 I am glad you do derivatives because I do not feel like finding the vertex. dV/dx = 864 -240 x + 12 x^2 0 = 72 - 20 x + x^2 x = [ 20 +/- sqrt(400 -288) ]/2 = [ 20 +/- 10.6 ] /2 = 15.3 or ...
March 20, 2015

physics
I can not because I do not know how far south the cat walked
March 17, 2015

physics
mg = 17*9.81 = 167 N weight 70 = mu (167) mu = 70/167 static 53 = mu (167) mu = 53/167 kinetic
March 17, 2015

Algebra
2 x^2 - 2 x - 2 = -y x^2 - x -1 = -(y/2) x^2 - x = -y/2 + 1 x^2 - x + 1/4 = -y/2 + 1 + 1/4 (x- 1/2)^2 = -(1/2) (y - 5/2) vertex at ( 1/2 , 5/2 ) if x = 6 y = - 2(36) + 12 + 2 = -58 =================== check (5.5)^2 =? -1/2 (-60.5) ??? 30.25 = 30.25 sure enough :)
March 17, 2015

math
2*60 + 2 w = 200 w + 60 = 100 w = 40
March 17, 2015

Math
1 % is .01 .02/5 is clearly less than .01 (it is .004) .2/5 is like .4/10 too big 2/5 even bigger 2/50 like 4/100 like .2/5 too big 2/500 is 4/1000 which is small enough (.004 again)
March 17, 2015

math
3/5 * 1/3 * x = 8 x = 8 * 15 / 3 x = 40 ================ check: 2/5 * 40 = 16 spent, 24 left 2/3 * 24 = 16 spent, 8 left --- sure enough
March 17, 2015

Vectors
vector QP = 3 i + 8 j + 2 k vector QR = 1 i + 6 j - 2 k cross product i j k 3 8 2 1 6 -2 -28 i + 8 j + 10 k or -14 i + 4 j + 5 k so for plane -14 x + 4 y + 5 z = d try (1,5,6) to get d -14 +20 + 30 = d d = 36 check with (-1,3,2) 14 + 12 + 10 = 36 sure enough we are on a roll ...
March 17, 2015

physics
(1/2) M V^2 = (1/2) K X^2 1330 v^2 = 4.12*10^6 (.0499)^2
March 17, 2015

Science Help Please
Your answer to umber 7 is likely to upset any physicist. Please read the chapter in your text. Go back to the chapters on waves on strings and in trumpets. short wave --> high frerquency
March 13, 2015

Science Help Please
2 A 5 D 6 A 7 D Oh dear :( 13 C
March 13, 2015

Math
38
March 13, 2015

physics
Huh? 500 Joules is 500 Joules.
March 13, 2015

PHYSICS
20 meters down pressure = rho g h = 1000kg/m^3*9.81*20 = 196,200 = 1.96 *10^5 Pascals I guess the radius is .4 m??? A = pi(.4)^2 F = P*A = 98,621 Newtons
March 13, 2015

vectors and geometry
2*5 + 3*-2 + 4*1 10 - 6 + 4 8
March 13, 2015

vectors and geometry
a+b = 6 i -1 j + 0 k trick question or typo cross product = |A||A| sin theta theta = 0 so cross product = 0
March 13, 2015

Check Answers (Math)
at x = 0, B is below at all other points, B is below so yes, right, B is wider.
March 10, 2015

physics
-19+6 = -13 so 1.6 * 10^-13 uC /electron so (1/1.6)*10^13 electrons/uC = .625 * 10^13 = 6.25 * 10^12 electrons
March 10, 2015

physics
assume light travels at very very high speed so you see the lightning immediately. Then distance = speed of sound * time distance in km = (1/3) t so speed of sound must be about 1/3 km/sec or about 333 m/s 8/3 km
March 10, 2015

MATH
right triangle, hypotenuse = 5.4 so sin I = JH/5.4 so JH = 5.4 sin 64
March 10, 2015

physics
G M/r^2 = .39 G M/Re^2 r^2 = Re^2/.39
March 9, 2015

physics
horizontal component of g = v^2/r g sin theta = v^2/r here g = 32 ft/s^2 v = 56 mi/h * 5280 ft/mi * 1 h/3600 s r = 1000 ft
March 9, 2015

maths(direction cosines of vectors)
change in x = 7 - 4 = 3 change in y = 6 - 2 = 4 change i z = 14 - 2 = 12 so V = 3 i + 4 j + 12 k is in the direction magnitude: sqrt (9+16+144) = 13 dot product with unit x vector for example V dot 1 i = 13 * 1 * cos angle so cos angle = 3/13 then y axis cos angle = 4/13 and x...
March 9, 2015

Calculus 1
2 x dx + 2 y dy = 2 (2 x^2+4 y^2 -x)(4 x dx + 8 y dy -dx) at (0, 1/4) 0 +(1/2)dy = 2(0+4(1/16)-0)(8(1/4)dy -dx) (1/2) dy = 2 (1/4)(2 dy-dx) = dy - (1/2) dx dy = 2 dy - dx dy = dx dy/dx = slope = 1 so y = x + b put in your point to find b
March 9, 2015

Calculus (Integral)
well, you could try this: http://www.wolframalpha.com/input/?i=integral&a=*C.integral-_*Calculator.dflt-&f2=25+%2F%28+e^x%2825+%2B+e^2x%29+%29+&f=Integral.integrand_25+%2F%28+e^x%2825+%2B+e^2x%29+%29+&a=*FVarOpt.1-_**-.***Integral.rangestart-.*Integral.rangeend--.**Integral....
March 9, 2015

math
I assume you mean: Factor 21 a^2 - 19 a - 22 well, we need -33 + 14 = -19 (7 a - 11)(3 a + 2)
March 8, 2015

math
2D * 3 D = 6 D^2 = 6 (2R)^2 = 24 R^2
March 8, 2015

5th grade Science
the density of water is about 1 g/cm^3 This boat is more dense than water, it is in fact more like a rock than most plastic and is certainly not hollow. the upward force on an object in water is the weight of water displaced by the volume of the object in the water. If the ...
March 8, 2015

Social studies
http://www.u-s-history.com/pages/h127.html
March 8, 2015

geography
Oh, the s makes it hard http://eos.ucs.uri.edu/EOSWebOPAC/OPAC/Details/Record.aspx?TaskCode=61612&BibCode=EOSMAIN|5127150|1|288252&HitCount=1&SelectionType=1&SearchType=2&CurrentPage=1&IndexCode=-1&SortDirection=Descending
March 8, 2015

geography
My students worked on one: https://eos.ucs.uri.edu/EOSWebOPAC/OPAC/Details/Record.aspx?TaskCode=61612&BibCode=EOSMAIN|5127150|1|288252&HitCount=1&SelectionType=1&SearchType=2&CurrentPage=1&IndexCode=-1&SortDirection=Descending
March 8, 2015

Physics
at (0,0) the fields from the first two charges cancel each other. to get a field at (0,0) in the y direction the x components of charges Q must cancel. Therefore one must be +Q and the other -Q If the field is up (+ i direction) the one below the axis is +Q and the one above ...
March 8, 2015

so what did you get ?
I already did this stuff in school. It is your turn to try. I suspect someone will check your results.
March 8, 2015

Math Functions
p = R - C = 5 x^2 + 19 x - 10 where is that zero? solve quadratic x = [ -19 +/- sqrt (361+200) ]/10 = [ -19 +/- 23.7 ]/10 = .469 thousand = 469
March 8, 2015

Physics
initial speed up Vi = 21 sin 37 v = Vi - 9.81 t at top v = 0 so t = ( 21 sin 37 ) / 9.81 = time rising time falling = time rising so 2 t = time in air
March 8, 2015

math
If only integer sides 1 , 10 , 1 nope sum of two must be > third 5 , 4 , 3 sure one 4 , 4 , 4 sure two 3, 3, 6 , nope, straight line 2 , 5 , 5 sure three 2 , 4 , 6 nope you found a fourth ?
March 8, 2015

math
do they have integer lengths? if so 2,5,5 4,4,4 5,4,3
March 8, 2015

math
Google Heron's formula Area^2 = A^2 = S(S-a)(S-b)(s-c) where S = (1/2) perimeter = 6 here so A^2 = 6 (6-a)(6-b)(6-c) so look for maximum of (6-a)(6-b)(6-c)
March 8, 2015

physics
It slows down, shorter wavelength, same frequency (note it can not change frequency. There is no storage of waves, the same number have to pass a given point per unit time on each side.) lambda = V * T so lambda = V/f if V goes down/ lambda goes down
March 8, 2015

College Math
e^rt = e^(.062*7) = 1.543418868 times $ 2600 = $ 4012.89
March 8, 2015

Maths
if you mean in radians 55 deg * (pi rad/180 deg) .9599 radians
March 8, 2015

physics
Every turn you go one circumference, 2 pi R
March 8, 2015

physics
must know radius R C = 2 pi R so 500 * 2 pi R
March 8, 2015

Algebra 2
if so then 5 -2.5 sqrt 3 + 2.5 i -2.5 sqrt 3 - 2.5 i
March 8, 2015

Algebra 2
x^3 = 125 x = 5 works you do not say if you also do complex numbers
March 8, 2015

physics
40 * 5 60 * 5 * 0.40 Joules
March 7, 2015

physics
force down = m g = 63*9.81 N mass accelerated = 63+10 = 73 kg a = F/m = 9.81 (63/73) m/s^2
March 6, 2015

Social Studies
Although the astrolabe has origins traced back over 1,500 years, it was highly developed in the Islamic world by 800 and was introduced to Europe from Islamic Spain (Andalusia) in the early 12th century. It was the most popular astronomical instrument until about 1650, when it...
March 6, 2015

linear programming - suspect not correct problem statement
x = paper y = cans p = 500 x + 350 y y </= 200 x </= 200 x >/= 10 y >/= 80 I do not understand last constraint, redundant if y</=200 rectangle corners at (10, 80) (10,200) (200, 80) (200,200) well, go ahead and evaluate p at each corner but obviously mas at (...
March 6, 2015

algebra
6, 12, 18, 24 is 4 4/24 = 1/6 1 - 1/6 = 5/6 permutations of 12 things 4 at a time is n!/(n-r)! = 12!/8! = 12 * 11 * 10 * 9 = 11,880 if it is a number I would call it quatitative.
March 6, 2015

Math
B 5 to 15 is one to three not one to five C 3/5 = painting/sculpture so 3/8 = painting/total 5/8 = sculpture/total 3/8 * 24 = 9 5/8 * 24 = 15
March 3, 2015

maths
45 = 5*3*3 60 = 5*3 *2*2 so we need 5*3*3*2*2 = 180
February 28, 2015

Physics
North: 4 + 1.2 sin 35 East 1.2 cos 35 + 1.3
February 28, 2015

Math
That seems to work.
February 28, 2015

Physics
Vi = 26.5 sin 30.9 = 13.6 v = Vi - g t at top v = 0 9.81 t = 13.6 at top t = 1.39 seconds up u = 26.5 cos 30.9 u = 22.7 d = u t = 22.7*1.39 = 31.6 meters
February 28, 2015

Physics
Weight does not matter. v = sqrt (2 g h)
February 27, 2015

statistics
http://davidmlane.com/hyperstat/z_table.html
February 27, 2015

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