Tuesday

February 21, 2017
Total # Posts: 29,370

**Mathematics**

50 (30/25) = 2*30 = 60

*December 22, 2016*

**Social Studies**

Where should I start???? Load and unload ships, trucks, trains, and planes or in the case of ports at the mouth of rivers (New Orleans, Rotterdam), transfer cargo between river barges and seagoing ships. Builds and repair ships and port facilities. Do the paper work and number...

*December 21, 2016*

**math**

(0,5800) and (5,7420) (7420-5800)/5 = (y-5800)/(x-0)

*December 21, 2016*

**math**

Well I showed you that the first choice is NOT a solution to the equation. However It might not be the only one. Check them all.

*December 20, 2016*

**math**

Try each of them for example -52 = -5(10) - 4 -52 = -54 I do not think so check the others as well.

*December 20, 2016*

**Math**

You are welcome.

*December 20, 2016*

**Math**

L,w,h area = 2 Lw + 2 Lh + 2wh = 600 so Lw+Lh+wh = 300 but L = 3w so 3 w^2 + 4 w h = 300 now V = L w h = 3 w^2 h so h = V/3w^2 3 w^2 + 4 w(V/3w^2) = 300 4 V/3w = 300 - 3 w^2 (4/3)V = 300 w - 3 w^3 we want d(4/3)V /dw = 0 300 = 9 w^2 w = (10/3)sqrt 3 L = 10 sqrt 3 w L = 100 so...

*December 20, 2016*

**physics**

I agree but wonder about the straight line. There is not enough gravity to hold them down, but there is still a force toward the earth center so I think the departure path would curve.

*December 20, 2016*

**Math**

You never know who will be online. All you can do is post the question. There are a lot of math teachers who check in here.

*December 20, 2016*

**Math**

Yep, it's right :)

*December 20, 2016*

**calculus**

right triangle 3,4,5 or 60,80,100 x= 60 y = 80 z = hypotenuse = 100 dx/dt = 80 dy/dt = 100 z^2 = x^2+y^2 2 z dz = 2 x dx + 2 y dy z dz/dt = xdx/dt +y dy/dt 100 dz/dt =60*80+80*100 dz/dt = 6*8+80 dz/dt = 128 km/hr

*December 20, 2016*

**History**

Heavens! Look at a map. What is the biggest river in the now United States? Texas where the beef comes from for Richmond is west of the river. Remember that fleet coming up from the Gulf of Mexico ("Damn the torpedoes" :)

*December 20, 2016*

**another no way**

You try first. I already took the course.

*December 20, 2016*

**No way**

I do not see any attempt by you to do these problems. I already took this subject and do not need the practice. You try first. Also read what you typed.

*December 20, 2016*

**Math**

25-13 = 12 which is the sum of the two bases at the ends h is the height area of rectangle in the middle = 13 h x is base of one triangle (below the 10) so 12-x is the other(below the 15 (12-x)^2 + h^2 = 225 x^2+h^2 = 100 ---------------------subtract 144-24x = 125 x = 19/24 ...

*December 20, 2016*

**math**

(9/14)(35,000) =

*December 20, 2016*

**Math**

Yes but do the division 9/3 = 3 laps/min 30/6 = 5 laps/min 20/5 = 4 laps/min Mary does the most laps /min

*December 20, 2016*

**math**

s = 3d d + 3d = 116 4 d = 116 d = 29 so s = 87

*December 20, 2016*

**Math (please help!!)**

It is also the incenter B http://www.google.com/search?q=incenter+of+triangle&ie=utf-8&oe=utf-8 and point of concurrency C http://www.google.com/search?q=iconcurrency+of+perpendicular+bisectors&ie=utf-8&oe=utf-8 and D

*December 20, 2016*

**30 to what ?**

30deg to horizontal or vertical? In either case, use Snell's law.

*December 20, 2016*

**math**

5 per year 5*20 = 100 twenty years

*December 20, 2016*

**history**

Clove production, slaves See: www.blackpast.org › Geography: Global African › Africa › KenyaSeyyid Said, also known as Said ibn Sultan, was a resourceful and energetic sultan ... moved the capital from Arabia to Zanzibar in order to initiate clove production...

*December 20, 2016*

**Social Studies**

push --> potato famine and nasty bosses drive people out pull ---> jobs and land draw those people as immigrants to Ellis Island.

*December 19, 2016*

**calcululs help me**

4x^2+8xy+9y^2-8x-24y+4=0 8xdx+8xdy+8ydx+18ydy-8dx-24dy=0 (8x+18y-24)dy= -(8x+8y-8)dx dy/dx = (-4x-4y+4)/(4x+9y-12)agree numerator = 0 when x+y=1 yes find d/dx(dy/dx)of (-4x-4y+4)/(4x+9y-12) = [(4x+9y-12)(-4dx-4dy)-(-4x-4y+4)(4dx+9dy)]/dx[(4x+9y-12)]^2 =4[(4x+9y-12)(-dx-dy)+(+...

*December 19, 2016*

**chemistry**

ZnO + 2HCl ---> ZnCl2 + H2O By the way H2O is ...... Zn = 65 g/mol O = 16 g/mol H = 1 g/mol Cl =35.5 g/mol 13.64 g ZnCl2 * 1 mol/(65+71)g = mols of ZnCl2 now you should be able to continue.

*December 19, 2016*

**American History**

I think A) http://millercenter.org/president/biography/monroe-foreign-affairs

*December 19, 2016*

**error !**

I multiplied by distance not time average speed = v/2 distance = .25 = t (v/2) t = .5/v then 3 v = 20 *.5/v 3 v^2 =10 v^2 = 10/3 v = sqrt(10/3) ================== check 3 v = 20 * t 3 sqrt (10/3)= 20 * .5/sqrt(10/3) 3 (10/3) = 20 * .5 yes

*December 19, 2016*

**physics**

change in momentum = force * time 3 v = 20*.25

*December 19, 2016*

**algebra 2**

ticket price p = 231/n p-4.5 = 231/(n+3) 231/n - 4.5 = 231/(n+3) 231(n+3)-4.5(n^2+3n) = 231 n 231*3 -4.5 n^2 - 13.5n = 0 4.5 n^2 + 13.5 n - 693 = 0 n = 11 or -14 so 11 =========================== check 231/11 = 21 231/14 = 16.5 yes, diff = 4.50

*December 19, 2016*

**Physics**

In other words unless there was energy input from a explosion on impact or something, no way the big block took off at 4.0 m/s

*December 18, 2016*

**Physics**

huh? .5*5 *2.9^2+.5*10*2.1^2 = 43.1 Joules .5*5 *0.9^2 + .5*10* 4^2 = 81.1 81.1-43.1 = 38 Joules more Something exploded :)

*December 18, 2016*

**American History**

ah come on !!!!

*December 18, 2016*

**calculus**

I assume you mean x^2 - x y - y^2 = 5 2 x dx - x dy -y dx - 2 y dy = 0 (2y-x)dy = (2x-y)dx dy/dx = (2x-y)/(2y-x) slope is undefined (vertical) when 2y-x = 0 or x = 2y so x^2 - x y - y^2 = 5 4y^2 -2y^2-y^2 = 5 y = +/-sqrt 5 then x = +/- 2 sqrt 5

*December 17, 2016*

**calculus**

surface area in m^2/radius in meters is meters radians is arc, no units so meters per radian

*December 17, 2016*

**algebra**

If any one of those three factors is zero, then the product is zero so z = 0 works z-1 = 0 works so z = 1 works z+3 = 0 works so z = -3 works therefore z = 0 or 1 or -3

*December 17, 2016*

**Algebra 1- Urgent**

In your table in part B the ratio is for example 10406.04/10303.01 = 1.01 check: 10303.01/10201 = 1.01 sure enough so that is increasing by ONLY ONE percent per year

*December 17, 2016*

**I do not believe you**

I think you have a very fundamental typo. We are talking about a constant rate of inflation here I bet you mean f(x) = 0.69 (1.03)^x in other words TO THE POWER x that would be 0.69 when x = 0 years, now 0.69 * 1.03 after one year 0.69 * 1.03 *1.03 after two years 0.69 *1.03*1...

*December 17, 2016*

**Algebra 1- Help please**

option 1 is not linear because it does not change by the same amount every year. It does not have a constant slope. option 2 increases by 100 per year, constant slope, straight line, linear ----------------------- a = A y^n 1100 =A y 1210 = Ay^2 1331 = A y^3 --------------- ...

*December 17, 2016*

**SS, PLZ HELP ME FAST!!!!**

hint: Japanese eat a lot more fish than people on the great plains eat.

*December 17, 2016*

**Calculus!! HELP!!**

1) The sides of the triangle shown increase in such a way that (dz/dt=1) and (dx/dt=(3dy/dx)) At the instant when x = 12 and y = 5, what is the value of dx/dt? ========================= You do not say but I suspect this is a 5,12,13 right triangle. If I am guessing right about...

*December 17, 2016*

**Maths**

I do not know what using rotational axis means but this is an ellipse 4(x^2-2x) +9(y^2+6y) = -4 complete squares 4(x^2-2x+1)-4+9(y^2+6y+9)-81=-4 4(x-1)^2 +9(x+3)^2 = 81 (x-1)^2/4.5^2 + (x+3)^2/3^2 = 1 ellipse

*December 17, 2016*

**Math**

area = (1/2)12*5 = 30 hypotenuse BC = 13 the area = 30 = (1/2)13*AD AD =60/13

*December 17, 2016*

**Math**

120,000/50 = 240,000/100 = 2400

*December 17, 2016*

**Probability and distribution**

16 total to start I could draw a white, then blue 6/16 * 7/15 or I could draw a blue, then white 7/16 * 6/15 add them 2(42/240) = .35

*December 17, 2016*

**math**

Try then (a^9/2)^3 = a^27/ 8

*December 16, 2016*

**History homework question**

Oh, 20th Century Leaders :) Civil Disobedience.

*December 16, 2016*

**History homework question**

Hudson River school is paintings. I do not understand the second question.

*December 16, 2016*

**American history**

well, if only about in Americas (not India, Africa etc) Spain - get gold out, make Catholics France - get fur and fish out, make Catholics. Do not send many French people, just a few missionaries and trappers. England - make trading partners that grow food and ship masts and ...

*December 16, 2016*

**physics**

v = omega r 10 = omega(2) omega = 5 radians/second Ac = v^2/r = omega^2 r = 25*2 = 50 m/s^2 F = m a = .5 *50 = 25 N (not 25.5)

*December 16, 2016*

**is (-2x)^-3 3 root of -2x?**

(-2x)^-3 = 1/(-2x)^2 = 1/[-2x(-2x)(-2x)] = 1/[(-8)(x^3)] =-1/(8 x^3)

*December 16, 2016*

**Maths**

subtract area of inside circle from area of outside circle radius inside = 28/2 = 14 radius outside = 14+3.5 = 17.5 so pi(17.5^2-14^2)

*December 16, 2016*

**Huh**

Your minister of education has two brains and they are headed for somewhere else?

*December 16, 2016*

**Jong**

Hair?

*December 16, 2016*

**typo**

x = 1 and y = 1 at t = 0 y = .5 x + b 1 = .5 + b b = .5 y = .5 x + .5

*December 16, 2016*

**calc**

y = sin t + cos^2 t - sin^2 t dy/dt = cos t -2cost sint -2 sint cost at t = 0 dy/dt = 1 x = cos t +2 sin t cos t dx/dt = -sint -2sin^2t+2 cos^2t at t = 0 dx/dt = 2 dy/dt / dx/dt = 1/2 = slope x = 1 and y = 1 at t = 0 y = 1 x + b b = 0 y = x

*December 16, 2016*

**Math**

1/(x+h) - 1/x (x - x - h)/(x^2+xh) -h/(x^2+xh) divide by h -1/(x^2+xh) let h--->0 -1/x^2 sure enough

*December 16, 2016*

**linear programming problem**

the intersection with p max is of 5x+10y=560 and 50x+20y=1600 x = 12, y=50 and p = 3220 http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=1e692c6f72587b2cbd3e7be018fd8960&title=Linear%20Programming%20Calculator&theme=blue

*December 16, 2016*

**calculus!**

at x+h y = 1/(3-x-h) at x y = 1/(3-x) subtract 1/(3-x-h) -1/(3-x) [(3-x) -(3-x-h)]/[(3-x-h)(3-x)] [ h]/[ x^2-6x+xh-3h+9] divide by h 1/[x^2-6x+9 +xh-3h] let h --->0 1/(x-3)^2

*December 16, 2016*

**Math - Coordinate Geometry**

3y = 2 x + 3 is y = (2/3)x + 1 slope = 2/3 so y = (2/3)x + b if parallel -4 = (2/3)6 + b b = -8 so y = (2/3)x-8 3 y = 2 x - 24

*December 16, 2016*

**math**

3078+582 = 3660 =3*1000 + 0*100 + 7*10 +8*1 +0*1000 + 5*100 + 8*10 +2*1 =3*1000 + 5*100 +15*10 +10*1 =3*1000 + 6*100 + 5*10 +10*1 =3*1000 + 6*100 + 6*10 + 0*1 = 3660

*December 16, 2016*

**Science**

Now I am sure you know these answers (although I consider a fossil biological). I would be willing to review them but not just answer them.

*December 16, 2016*

**Geometry**

I guess it is supposed to be a triangle? If so ac can not be longer than 11+13 = 24 and it can not be shorter than 13-11 = 2 DRAW IT !

*December 16, 2016*

**Sociology**

They mean the same thing to me. Homogeneous is opposite to diverse.

*December 16, 2016*

**calculus**

LOL, either way I do physics, I find t easier to visualize step by step.

*December 16, 2016*

**calculus**

dV/dt = 3ft^3/min(1 min/60s) = .05 ft^3/s so V = .05 * 30 = 1.5 ft^3 at 30 s V = (4/3) pi r^3 so r = 0.71 ft at 30 s dV/dr = 4 pi r^2 (the surface area of course) but dV/dt = dV/dr * dr/dt so dr/dt = dV/dt / (4 pi r^2) dr/dt = .05 /(4 pi*.71^2) = .00789 feet/second

*December 16, 2016*

**Gauss-Jordan elimination**

-3 +3 -21 +3 +2 -4 ============= http://www.idomaths.com/gauss_jordan.php ===================== 1 0 2 0 1 -5 x= 2, y = -5

*December 15, 2016*

**HELP SCIENCE**

Which do you think? What does north and south pole mean?

*December 15, 2016*

**augmented matrix**

No unique solution, equations are the same +3 +1 -11 -9 -3 +33 http://www.idomaths.com/gauss_jordan.php 1 0 -3.667 0 0 0 x = -3.6666.... or -11/3 y can be anything equation 2 is -3 times equation 1 Therefore the two lines are the same, they do not intersect, there is no solution

*December 15, 2016*

**Physics**

3.) An 80.kg climber with a 20.0 kg pack climbs 8848 m to the t?op of mount everest. how much work did the climber exert in the climbing the mountain ==================== 100 kg up 8848 meters 100 * 9.81 * 8848 = 8,679,888 Joules (That is the useful work, his efficiency would ...

*December 15, 2016*

**Physics**

When the string is cut, the bob has only horizontal velocity u. It keeps that horizontal velocity u until it hits the ground because there is no horizontal force after that. So there are two separate problems here: 1. How far does it go at constant speed u for time t? 2. If ...

*December 15, 2016*

**Math 4th Grade**

You are welcome, good luck.

*December 15, 2016*

**Math 4th Grade**

280 = 2 x m 28 = 2 x 14 280 = 2 x 140 so m = 140 I am not sure why I would want to do it that way though. If you can handle 2 x 14 I bet you could handle the tens part.

*December 15, 2016*

**Sets**

Union is 107 Intersection is 13 draw Venn diagram 69 + A alone = 107 so A alone = 38 plus A and B = 38+13 = 51

*December 15, 2016*

**Measurement/math**

35*circumference = 100

*December 15, 2016*

**Algebra**

check it yourself like this: 11 + (-.7) = -15(y) ????? I think x = 19 and y = -2 http://www.idomaths.com/gauss_jordan.php with +1 15 -11 +2 -5 +48

*December 15, 2016*

**Math**

1/4 + what = 11/12 ???? 3/12 + what = 11/12 well how about 8/12 so 1/4 + 8/12 = 11/12 or 1/4 + 2/3 = 11/12

*December 15, 2016*

**Algebra II**

What is an L ?? Perhaps a Newton??? if cm^2/then D for Dyne anyway v = k/p 16 cm^3 = k / 20L/cm^2 k = 16*20 v = 16*20/2.2 = 145 cm^3

*December 15, 2016*

**maths calculas part**

144/4 = 36 36*36 = 1296 m^2 now how did I know it was square? 2x+2y = p = perimeter so x+y = p/2 so y = p/2-x A = x y = x(p/2-x) A = (p/2)x - x^2 or x^2 - (p/2)x = - A x^2 -(p/2)x + (p/4)^2 = -A + p^2/16 [ x - (p/4)]^2 = - (A-p^2/16) so vertex at area = (p/4)^2 and x = y = p/4...

*December 15, 2016*

**Maths**

if there are five of them and the median is five I think five is an integer a b c d e c = 5 (a+b+c+d +e)/5 = 5 so a+b+5+d+e = 25 a+b+d+e=20 with d and e >5 and a and b <5 well what if a = 1 b= 2 d= 7 e = 10 1 2 5 7 10

*December 14, 2016*

**precalculus**

P(k+1) = p(k) + 5

*December 14, 2016*

**Math**

volume is proportional to length cubed for similar geometry 2 times length is 4 times area 2 times length is 8 times volume so 1875(16/40)^3 = 1875(.064) = 120cm^3

*December 14, 2016*

**physics**

centripetal acceleration: To stay at the same radius, a water particle of mass m must have a force on it inward of m v^2/r. Until it hits the walls of the container, that force is missing. If the water particle happens to hit upon a hole in the wall or dribbles down the wall, ...

*December 14, 2016*

**Science 6**

B skunk eats toads I do not think toads and mice compete for who has the honor of being eaten by the fox

*December 14, 2016*

**Algebra**

1 q + 1 n = 13 1 q + .2n = 8.2 ---------------subtract .8 n = 4.8 so 6 nickels

*December 14, 2016*

**precalculus**

as you can see in the other answers, yes 4y^2+8y-2

*December 14, 2016*

**precalculus**

I guess you might mean: x = t^2-6 y = .5t - 1 ????? if so, just substitute 2y = t -2 t = 2 y +2 then x = 4(y^2+2y+1) -6 x = 4y^2 + 8y - 2 sketch that parabola

*December 14, 2016*

**precalculus**

hyperbola opening right and left center at (0,0) crosses x axis at -1 and +1 slopes at corners = +/- 2

*December 13, 2016*

**linear programming**

maximize p p = 6s+5b s+b</=70 b>/=20 s>/=10 sketch a graph there are two intersections to check (s,b) = (10,60) here p= 60+300 = 360 and (s,b) = (50 ,20) here p=300 + 100 = 400 (winner)

*December 13, 2016*

**physics**

Fup = 400 Fdown = 9.81*50 =491 so accelerating down a down = 91/50 m/s^2

*December 13, 2016*

**Science-y Math-y Stuff**

0.8 x = 4,000

*December 13, 2016*

**Science**

There was this guy in Sicily , Archimedes: http://www.math.nyu.edu/~crorres/Archimedes/Lever/LeverIntro.html http://en.wikipedia.org/wiki/Lever

*December 13, 2016*

**Physics**

alternatively you can use conservation of energy kinetic energy at bottom = potenial energy at top (1/2)mVi^2 = m g h so Vi^2 = (2 g h) h = Vi^2/2g

*December 13, 2016*

**Physics**

get vetical component of velocity up at ground, call it Vi. If shot at angle A up from horizontal then Vi = V sin A during flight acceleration = -g or 9.8 m/s^2 down or 32 ft/s^2 down speed up = v = Vi - g t = Vi -9.8 t or = Vi -32 t at top, v = 0 so t = Vi/9.8 or t = Vi/32 ...

*December 13, 2016*

**Physics**

average speed during initial slowdown = (80+40)/2 = 60km/h 60 km/h * t = 0.5 km t = 5/600 hours = (1/120)hr (1 hr/120)(60min/hr)(60s/min) = 30 seconds so a = change in speed/time = -40 km/hr /30 s = (-40 * 1000 m/3600s)/30s = -(4/3)/3.6 m/s^2 so Vi = (40/3.6) m/s final v = 0 =...

*December 13, 2016*

**I THINK I FIGURED IT OUT!**

8 works if you reverse order

*December 13, 2016*

**Math**

2/5 = 10/x x = 25

*December 12, 2016*

**Pre-Calculus**

well if you mean (x^2-1) it is D but if you really mean (lim x^2) -1 which is what you typed it is A

*December 12, 2016*

**Algebra**

9(r-2)<-73 or 9(-r+2)<-73 first one: 9 r -18 < -73 9 r < -55 r < -55/9 sure looks like a solution second one: -9 r + 18 <-73 9 r -18 > 73 9 r > 91 r >91/9 so second solution

*December 12, 2016*

**pre-calculus**

square :) side = 50/4 = 25/2 A = x y P = 2x+2y = 50 so y = (25-x) A = x(25-x) = 25 x - x^2 x^2 -25 x = -A x^2 - 25 x + (25/2)^2 = -A + 625/4 x = 25/2 sure enough so y = 25/2 and A = 625/4 = (25/2)^2

*December 12, 2016*

**Algebra**

1. 8 is a factor of 12?? 12/8 = 3/2 = 1.5 2 55/5 = 11 3. You said what P was 4 and 5 are incomplete problem statements both A and B are subsets of U 2 is the intersection of A and B

*December 12, 2016*