Monday
July 25, 2016

Posts by Damon

Total # Posts: 26,544

Pre Cal
assume you mean x^2 + y^2 = 0 That is a circle of zero radius with center at the origin :) In other words a dot at the origin.
February 25, 2016

Science
Looks like it reacted chemically with something in the air to me :)
February 25, 2016

math
first one black = 26/52 = 1/2 second one black = 25/51 third one black = 24/50 fourth one black = 23/49 etc until we get to number 12 then multiply all those fractions that means you got every king, queen and jack 4 kings + 4 queens + 4 jacks = 12 of the 52 card 1 = 12/52 ...
February 25, 2016

MATH
3 x - y = 4 3 x - y = 6 never cross -parallel, no solution 2 x - y = 1 3 x + y = 6 --------------add 5 x = 7 x = 7/5 etc 1 x - 5 y = 5 3 x + 1 y = 7 multiply first by 3 3 x -15 y = 15 3 x + 1 y = 7 ---------------subtract -16 y = 8 y = -1/2 etc
February 24, 2016

Math
21 * 7 = (1 - 5/8) p = (3/8) p p = 49*8 = 382 pages
February 24, 2016

Algebra
y = - x^3 no y = -3^x would be but not this
February 24, 2016

Algebra: Check Answer
LOL no need to ask, plug back in h = -16(10.4)^2 + 156(10.4) +105 = -1730.56 + 1622.4 + 105 = -1730.56 + 1727.4 close enough to the ground :)
February 24, 2016

Math
Yes dA/dr = 2 pi r = 6.28 r correct however think a little more dA = 2 pi r dr = circumference * dr If you draw a picture of a circle r and then one outside it with radius r + dr You will see immediately that the change in area is the strip of length 2 pi r times the width dr
February 24, 2016

Math
dA = 2 pi r dr yes, correct however notice that this is simply the circumference the new area added is the circumference * dr
February 24, 2016

math
Yes we agree but I simplified
February 24, 2016

math
I assume dy/dx=(4sqrt(y)ln x)/x y^-.5 dy = 4 (ln x /x)dx y^.5 = 2 [ .5 ln^2 x ] y^.5 = ln^2 x y = ln^4 x + c
February 24, 2016

Physics
bullet momentum = .017 v total mass = .017+1.2 = 1.217 kg final momentum = initial momentum .017 v = 1.217 V' V' = .014 v normal force on table = m g = 1.217 (9.81) friction force = .23*1.217*9.81 = 2.75 Newtons work done = 2.75 *8.6 = 23.6 Joules so 23.6 =(1/2)mV'...
February 24, 2016

Algebra 2
yes all 3 are correct but it is easier to use sin and cos sin^-1 (3/19) and cos^-1 (18.8/19)
February 24, 2016

ALGEBRA
surface area = area of top + area of bottom + area of side = pi r^2 + pi r^2 + 2 pi r h = 2 pi (r^2+ r h) = 2 pi r (r + h) = 2 *pi*4 * 10 = 80 pi volume = pi r^2 h = pi *14 * 6 = 84 pi
February 24, 2016

Math
let z = y^.5 then dz = .5 y^-.5 dy dy = 2 y^.5 dz = 2 z dz 2 z dz /(z cos^2 (z) ) = x dx dz/( cos^2 (z)) = .5 x dx tan z = .25 x^2 + constant tan y^.5 = .25 x^2 + constant
February 24, 2016

Mensuration
Now I showed you how to do one by subtracting rectangles. You do this one.
February 24, 2016

Math
That is quite a markup : I have a sneaking suspicion that they mean 140% markup but will do it as stated .75 * price = 39.95 so usual price = 53.27 cost + 2.40 * cost = 53.27 3.40 * cost = 53.27 cost = 15.67 39.95 - 15.67 = 24.28
February 24, 2016

Trigonometry
m and j tan 30 = m/15 tan 45 = 1 = j/15 j - 15 and m = 15 tan 30 = 8.66 m+j = 23.7
February 24, 2016

Precalculus
sec 4x = 1/cos 4x I can not graph it for you here but note that cos 90 or pi/2 = 0 so you are going to have a bunch of vertical asymptotes
February 24, 2016

Mensuration
the original sheet is 30*20 = 600 cm^2 the remaining sheet is 30-8 by 20-8 or 22 * 12 = 264 cm^2 so you removed: 600 - 264
February 24, 2016

Calculus
pi/3 = 60 degree just so I do not have to use radians on my calculator :) c^2 = a^2 + b^2 - 2 a b cos C get initial stuff first cos 60 = 1/2 sin 60 = .866 c^2 = 64 + 169 - 208 cos 60 c^2 = 233 - 104 = 129 c = 11.4 now do the problem 2 c dc/dt = -208 (-sin 60) dC/dt so dc/dt = ...
February 24, 2016

Math
i = -75 p^2 + 600 p if p = 3 i = -75 (9) + 1800 1,125 = -75 p^2 + 600 p 75 p^2 -600 p + 1,125 = 0 solve quadratic for 2 values of p. Throw out any negative one etc for max I assume you do not know calculus so complete square to find vertex 75 p^2 - 600 p = -i p^2 - 8 p = -i/75...
February 24, 2016

statistics
I will do three cards, you do five. 52 cards, 26 are red so find probability of all black first draw 26/52 = 1/2 second draw 25/51 third draw 24/50 = 12/25 prob of all black =.5*25/51*12/25 =.118 so 1-.118 = .882 for at least one red in three draws
February 24, 2016

physics- check this out
v = Vi + a t v = 0 at stop a = -Vi/t = -35 m/s^2
February 24, 2016

Physics
7 t = d 13 t = d+42 so 6 t = 42 t = 7 7 t = d = 49
February 24, 2016

physics
A kilowatt is 1,000 Watts
February 24, 2016

Physics
I will have to guess at your drawing. Both objects fall the same. The first one keeps its horizontal velocity so both fall 1.14 meters v = g t = 9.81 t 1.14 = (1/2) g t^2 = 4.9 t^2 so t = 0.482 second fall time for both so vertical velocity of both is 9.81 * .482 = 4.73 m/s ...
February 24, 2016

physic
falls 63 m 63 = 4.9 t^2 calculate t which is time in air now range = 20 t the end.
February 24, 2016

physics
Kilo
February 24, 2016

physics
22.61 g/cm^3 * (100 cm/m)^3 (1kg/1000g) = 22,610 kg/m^3 by the way water is about 1000 kg/m^2
February 24, 2016

????
You forgot the equation
February 24, 2016

physics
20 east
February 24, 2016

physics
I assume you mean 8 hours. Velocity is the displacement /time and direction Here that is 320/8 or 40 mph North The 400 zigging and zagging is irrelevant for velocity but important if you wanted speed instead of velocity
February 24, 2016

please help
Please just do what I suggested. Goggle Mt Kilimanjaro and those countries.
February 24, 2016

African climates - where to start?
I do not know what to say. Except for one mountain (http://www.tanzaniaparks.com/kili.html) there is not much snow. However everything else is there :) Desert in the North, riverine in the Nile valley, jungle in the center and down the Congo river. Savannas, farmland, grazing ...
February 24, 2016

science
when the potential (voltage) is different in different places on the conductor.
February 21, 2016

Science
It doubles every (1/4) day? in 7 days it doubles 28 times 2^28 = 268,435,456
February 21, 2016

Science
Maybe you mean Bernoulli : (1/2)rho v^2 + rho g h + p = constant If flow is constant in time and no frictional losses rho = density h = altitude p = pressure g - gravitation acceleration v = speed
February 21, 2016

Physics
I can not sketch it for you. v = (2t+1.34) i + 3.34 j + (6t^2 - 8t) k so put in t = 2 a = 2 i + (12t-8) k again use 2 for t
February 21, 2016

Physics
A: v = 10 pi/(10.34) Ac = v^2/r = 20 pi^2/(10.34)^2 B: v = 20 pi/(10.34) Ac = 40 pi^2/(10.34)^2
February 21, 2016

Maths
(-4/3) x = 16/3 -4 x = 16 x = -4
February 21, 2016

science
60min/hr * 60 sec/min = 3600 seconds/hour 2 * 3600 + 35 = 7235
February 21, 2016

Chemistry
we are close to STP here where one mol is 22.4 liters 58.4/22.4 is around 2.61 moles 10.3/2.61 = 3.95 grams/mol Helium maybe ?
February 21, 2016

Algebra
Oh well, I'll play 300 = k * 3^2 * 10.62 so k = 300/(9*10.62) = 3.14 remarkable :) in fact v = pi r^2 h = pi * 3^2 * 10.62 = 300.27 :) so we say v = 3.14 * r^2 *h = 3.14 * 16 * 15.92 =785 cm^3
February 20, 2016

Physics
horizontal rope force= 100 cos 60 = 50 N so a) work done by tension = 50*15 = 750 Joules b) NONE !!!! there is no vertical displacement !
February 20, 2016

Math
.6 (299) = 179.4
February 20, 2016

math
I guess you mean circumference of a circle of radius 5.5 in if so 2 pi r = 11 pi
February 20, 2016

High school calculus
I have a extra b in there.
February 20, 2016

High school calculus
dy = (bx+5)^-3 dx let z = bx+5 then dz = b dx and dx = (1/b) dz dy = (1/b) z^-3 dz y = (1/b)(-1/2)z^-2 + c y = -1/(2b z^2) + c but z^2 = b^2x^2 + 10 bx + 25 so 2 b z^2 = 2b^3x^2 + 20 b^2 x + 50 b so y = -1/(2b^3x^2 + 20 b^2 x + 50 b) + c
February 20, 2016

Algebra
t = k r^2/z^3 4 = k 36/27 k = 3 so t = 3 r^2/z^3 ============================ c = k d^2/L .54 mho = k 3^2/50 k = 50 * .54 /9 = 3 again LOL (note - in your units which are not the ones a physicist would tend to use)
February 20, 2016

math
Some blame it on people like Pythagoras but I think folks along the Indus River thought it up to keep track of monsoons and crops and water level and stars and stuff. The really important guy was Sicilian but everyone calls him Greek named Archimedes. He not only figured out ...
February 20, 2016

phy 231
centripetal acceleration Ac = v^2/r = r omega^2 omega is part a r = radius there = Re sin 49 [ note - usually we use latitude which is angle North of the equator in this case cos(90-49)]
February 20, 2016

physics
(1/2) a t^2 = h (1/2)(9.81)(36) = h in meters
February 20, 2016

math
I can guess based on the possible answers. The only one with a y axis intercept is y = 5 x + 2 that is $2 to walk in the store and a unit rate of $5 per sandwich
February 19, 2016

Statistics
You are welcome.
February 19, 2016

Statistics
http://davidmlane.com/hyperstat/z_table.html
February 19, 2016

Math
http://www.jiskha.com/display.cgi?id=1455913440
February 19, 2016

Just did it
see below
February 19, 2016

Math
.80 * .75 * 179.99
February 19, 2016

physics
work output = 500 * 1.7 = 850 Joules work input = 1000 Joules efficiency = (850/1000)100 = 85 % since you did not say what the velocity ratio was, how would I know what the mechanical advantage was? They are the same on inverses depending of which way you write the velocity ...
February 19, 2016

chemistry
if they have more than one electron or lack of electrons in complete outer shell they can lose or gain electrons to form complete outer shells. Google oxidation reduction
February 18, 2016

Physics
100,000 meters/3600 seconds = 27.8 m/s d = 27.8 t d = (1/2)(3)(t-20)^2 so 18.5 t = t^2 -40 t + 400 solve quadratic for t
February 18, 2016

Chemistry
You do not say if you are in middle school, high school or college or what you are having trouble with. Google chemistry and you will find lots of stuff, for example: http://www.learnerstv.com/Free-chemistry-Video-lectures-ltv558-Page1.htm
February 17, 2016

huh?
Missing info, perhaps width of frame
February 17, 2016

Physics/Eletrical engineering
That is called a circuit.
February 17, 2016

Chemistry
5 grams of Na is 5/23 = .2174 mols so we get .2174 mols of NaBr NaBr = 23 + 80 = 103 grams/mol .2174 * 103 = 22.4 grams
February 17, 2016

Physics
http://www.jiskha.com/display.cgi?id=1455744206
February 17, 2016

Physics
Been there, done that. Check below
February 17, 2016

Calculus
If the first then dM/dt = -(1/3)(2t) + 1 = -2t/3 + 1 if t = 2 dM/dt = -4/3 + 3/3 = -1/3 the medicine is disappearing, presumably because it is eating bad guys.
February 17, 2016

Calculus Please use parentheses
-(1/3) t^2 + t or -1/(3 t^2) + t or 1/(3t^2+t)
February 17, 2016

math, simple math
which is e^(-x^2/a^2)
February 17, 2016

Physics
up 1 cm on 51 cm string cos A = 50/51 sin A = side force F/ Tension T tan A = F/(mg) so F/mg = tan 11.36 = .201 F = .001 (9.81)(.201) = .00197 Newtons F = Q E .00197 = Q * 9200 Q = 2.14 * 10^-7 Coulomb If motion in direction of E field, charge positive
February 17, 2016

physics
The center of mass will not accelerate, no external force on the system. That is a distance d from the 6000 kg asteroid 6000 d = 3580(400 -d) 6000 d = 1,432,000 -3580 d d = 149.5 meters from the asteroid so we need to pull the asteroid 149.5 meters 149.5 = (1/2) a t^2 where a...
February 17, 2016

math age problem
(r-2) , r , (r+8) 3 r + 6 = 60 3 r = 54 r = 18 so 16 , 18 , 26
February 17, 2016

whoops
sorry, use Reiny solution
February 17, 2016

Trig
cos 52 = (h-10.5) /12
February 17, 2016

algebra
one triangle is 20 by 30 the other is 30 by 30 sqrt(30^2+30^2) + sqrt(20^2+30^2)
February 17, 2016

chemistry
well, first it only has one electron. The spectrum gives you possible energy levels (states or orbit radius) for that electron.
February 16, 2016

math
h = 1000 x = sqrt (1250^2 - 1000^2) = 750 meters horizontal r = distance (hypotenuse) r^2 = h^2 + x^2 2 r dr/dt = 0 + 2 x dx/dt so dr/dt = (x/r) dx/dt = (750/1250)(800)
February 16, 2016

math
38 = 2 * 19 57 = 3 * 19 so 2/3
February 16, 2016

Algebra
Yes, an hour, 60 min
February 16, 2016

Algebra
stan speed = s lawns/min Hilda speed = 2s lawns/min (s + 2s) = total speed in lawns/min so (s + 2s) (20 min) = 1 lawn 60 s = 1 s = 1/60 lawns/min or 60 min/lawn
February 16, 2016

Algebra
80 t = 125 (t-1) 125 = 45 t t = 2.7777 hours or 2 hours and 47 min for car 1 and 1 hour and 47 minutes for car 2 check 80 * 2.777 = 222 125 * 1.777 = 222 good so 1 hour and 47 minutes
February 16, 2016

Algebra
420 - 20 = 400 420 + 5 = 425 so 400</= T </= 425
February 16, 2016

Algebra
8 parts total (3/8)(568) alcohol (5/8)(568) acid
February 16, 2016

Algebra
.04 x + .06 ( 67000-x) = 3440
February 16, 2016

math
I guess it starts at 0 height h = a x^2 + b x 148 = a (1)^2 + b(1) 272 = a(2)^2 + b(2) b = 148 - a 272 = 4 a + 2 (148-a) 272 = 4 a -2 a + 296 2 a = -24 a = -12 (should be 16 on earth but anyway) b = 148 +12 = 160 so h = -12 x^2 + 160 x if x = 6 h = -12*36 + 160(6) = 528
February 16, 2016

Algebra
f = 4 t 5 f + 10 t = 1050 so 20 t + 10 t = 1050 30 t = 1050 t = 35 tens
February 16, 2016

Help please? Math 141 (Pre-Cal)
as t gets huge the 84 and the 28 are small potatoes s ---> 51/3 = 17 16.5 = (51 t + 84)/(3t+28) solve for t
February 16, 2016

Math
are you doing geometric sequences maybe? 32 32*4.5 32*4.5^2 32*4.5^3 32 144 648 2916
February 16, 2016

Physics
Torque = I alpha Tension in line = T weight = m g = 1 * 9.8 = 9.8 N so 9.8 - T = 1(4.5) T = 5.3 N or kg m/s^2 torque = T * R = 5.3 R Nm or kg m^2/s^2 so 5.3 R kg m^2/s^2 = I alpha but a = alpha R so alpha = a/R so 5.3 R^2 kg m^3/s^2 = I kg m^2 * 4.5 m/s^2 I = 5.3 * .45^2 /4.5...
February 16, 2016

physics
assuming that then v = dx/dt = 2 A t + B a e^(at) acc = dv/dt = 2 A + B a^2 e^(at) now constraints at t = 0 -2 = B so 4 = -2 a a = -2 so in fact x = A t^2 -2 e^(-2t) v = 2 A t + 4 e^(-2t) acc = 2 A -8 e^(-2t) now at t = .2 , v = 5 so 5 = 2 A(.2) - 8 e^-.4 5 = .4 A - 5.36 A = ...
February 16, 2016

?
do you mean x = A t^2 + B e^(at) ?
February 16, 2016

Social Studies (Check, Please!)
Typo in #2 fight, they were old enough to fight. You mean VOTE
February 16, 2016

jewellry
Amma said to do what she typed, y = -3/x + 1
February 16, 2016

Math-asymptotes
ok if it is y = -(3/x) + 1 then clearly when x -->0 this becomes huge positive or negative depending on if x is positive or negative. That is the poit of vertical asymptotes as x becomes huge positive or negative, y---> 1 horizontal
February 16, 2016

huh?
do you mean y = -3/(x+1) or what you typed?
February 16, 2016

Math
2 cups / 36 cookies = x cups/ 60 cookies
February 16, 2016

Math
cran/gran = 1/3 1/3 = 3/x x = 9
February 16, 2016

Algebra
24.5 * 10^4 = 2.45 * 10^5 so yes, b
February 16, 2016

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