Tuesday

January 17, 2017
Total # Posts: 28,779

**Algebra 1**

You are welcome.

*January 7, 2017*

**Algebra 1**

a = b + 2 c b = 2 c so a = 2 c + 2c = 4 c a + b + c = 77 4 c + 2 c + c = 77 7 c = 77 c = 11

*January 7, 2017*

**math**

you could do this by dividing the areas but that is not safe because it might not be exact one way or the other so 6 * 1.5 = 9 8 * 1.5 = 12 6*8 = 48 exactly

*January 7, 2017*

**Math**

4b+2p = 34 p = b-4 4 b + 2(b-4) = 34 4 b + 2 b - 8 = 34 6 b = 42 b = 7

*January 7, 2017*

**algebra**

3 z^2 = -108 z^2 = -36 z = +/-6 sqrt -1 = +/- 6i

*January 7, 2017*

**algebra**

5 x^2 = 651-536 = 115 x^2 = 23 x = +/- sqrt 23 = +/- 4.80

*January 7, 2017*

**Math**

49 - 2v

*January 7, 2017*

**Math**

three choices for the first digit 2 choices for the second 1 choice for the third 3*2*1 = 6 1 2 3 1 3 2 2 1 3 2 3 1 3 1 2 3 2 1

*January 7, 2017*

**algebra**

54 = 2*27 = 2*3*3*3 6 and 9 is 15 so (w-6)(w-9)

*January 7, 2017*

**Calculus**

5[xdy + ydx ] +x^2 dy+y(2x dx)=0 dy(5x +x^2) + dx(5y+2xy) = 0 dy/dx = =(5y+2xy)/(x^2+5x)

*January 6, 2017*

**Chemistry**

Ph determination

*January 6, 2017*

**Chem 111**

1000 kg/m^3 V = pi (d^2/4)h d = 6 ft = 1.83 m h = 17.5 ft = 5.33 m so V = [pi(1.83^2)/4 ]5.33 m^3 mass= 1000 * V in kg there are about 2.2 pounds/kg

*January 6, 2017*

**Math**

(2*27 + n)/3 = 29 54 + n = 87 n = 33

*January 6, 2017*

**Need help with vector questions posted below**

+1 1 3 -1 2 n +2 m 1 determinant = 0 2 + 2n -3m -12 -nm +1 = 0 2n-9 -m(3+n) = 0 m = (2n-9)/(3+n)

*January 6, 2017*

**maths**

everything in thousands two points on line (4,22) and (6,30) (30-22)/(6-4) = slope so slope = m = 4 c = 4 n + b 22 = 16 + b b = 6 so c = 4 n + 6 if n = 4.5 c = 4(4.5) + 6 c = 18+6 c = 24 so 24,000

*January 6, 2017*

**Vectors - Maths [Second Question]**

+1 -1 +2 +1 +2 -4 +m +6 -12 det = 0 -24 +12 +4m -4m +24 -12 = 0 I get any old m

*January 5, 2017*

**Vectors - Maths**

+1 1 3 -1 2 n +2 m 1 determinant = 0 2 + 2n -3m -12 -nm +1 = 0 2n-9 -m(3+n) = 0 m = (2n-9)/(3+n)

*January 5, 2017*

**calculus**

f(x+h) = 1/(2x+2h) f(x) = 1/2x f(x+h)-f(x) = (2x -2x-2h)/2x(2x+2h) = -2h/(4x^2+4xh) divide by h = -2/(4x^2+ 4xh) let h--->0 = -2/4x^2 = -1/2x^2

*January 5, 2017*

**Calculus**

Oh well h = 9 cm r = (6/12)9 = 4.5 cm dV = pi r^2 dh so dV/dt = pi r^2 dh/dt -3 cm^3/min = pi (4.5)^2 dh/dt so dh/dt = -3/[ pi(4.5)^2] about .047 cm/min

*January 5, 2017*

**Calculus**

No. The answer is in cm/min not cm^4/min. I did not check the arithmetic.

*January 5, 2017*

**Calculus**

I and also Steve have answered a million of these. For example: http://www.jiskha.com/display.cgi?id=1415757944

*January 5, 2017*

**incomplete**

earned how much in a year, call it x percent = 100 (x/9000)

*January 5, 2017*

**Maths**

By the way for small angles most of us assume sin theta = tan theta = angle in radians where angle in radians = angle in degrees * pi/180 then the arc length = chord length = R theta

*January 5, 2017*

**Maths**

LOL, If you really want to do it as an isoceles triangle with equal legs of length 5.06 e13 miles then sin .5 minutes = (x/2)/5.06e13 x = 5.06 e13 * 2 sin .5 min sin .5 min = sin (.5/60) degrees = .000145441 times 10.12 e13 = .00147186292 e13 = 1.47 e10 again:)

*January 5, 2017*

**my typo**

found error so your arc length in light years is 2 pi(8.611)/(60*360) = .0025048 light years which is 1.47e10 miles (those are land, not nautical miles) To get it go to Google and type .0025048 light years = miles and hit enter or use calculator and speed of light.

*January 5, 2017*

**Maths**

Clearly parallax is not a problem at this distance :)

*January 5, 2017*

**Maths**

You are right, I have an arithmetic error I estimate that 8.6 light years ia about 5.06 * 10^13 or 5.06e13 miles one minute is 1/21,600 of the circumference [ that is 1/(360*60) because 360 degree and 60 minutes per degree] circumference = 2 pi r = 2 pi * 5.06e13 = about 31 ...

*January 5, 2017*

**Maths**

for that pesky e notation: http://www.mathsisfun.com/numbers/scientific-notation.html look at example at the end: Example: 3.12E4 is the same as 3.12 × 104 3.12E4 = 3.12 × 10 × 10 × 10 × 10 = 31,200

*January 5, 2017*

**Maths**

Oh my, you really need another bit of spherical trig, namely the measure of an angle in "radians" there are 2 pi radians in a circle of 360 degrees so the circumference is C = 2 pi radians * R the handy thing is for any angle in radians now arc length along circle = ...

*January 5, 2017*

**Maths**

2*1.5 = 3 m^2

*January 5, 2017*

**physics (mechanics)**

dU = work done=potential change or force dr = dU U = A/r dU/dr = F = -A/r^2 Sign of A depends on attractive or repulsive.

*January 5, 2017*

**Pre Calc**

These are straight lines, they cross once. 2.4 +.3 t = 1.1 + .7 t .4 t = 1.3 t = 13/4 = 3 1/4 years

*January 4, 2017*

**Math**

pre tax = 1.18 p 1.18 p * 1.06 = 37.20 so p = 37.20 / (1.18*1.06)

*January 4, 2017*

**math - calculus help!**

oh well, not that hard V = (1/3)pi r^2 h r = 7 h/24 so V = (1/3)pi (7/24)^2 h^3 dV/dh = pi (7/24)^2 h^2 dh when h = 10 dV = pi (70/24)^2 dh dV = pi (35/12)^2 dh

*January 4, 2017*

**math - calculus help!**

You could use a fancy formula for volume of a cone and differentiate it to find dV/dh but if you just draw a picture you can see that the area of the surface * dh is the added volume for added dh

*January 4, 2017*

**math - calculus help!**

radius/depth = 7/24 what is radius when depth = 10? 7/24 = r/10 r = 70/24 = 35/12 now the change of volume with depth h is the surface area area * dh = dV pi r^2 dh = dV pi r^2 dh/dt = dV/dt = 12 ft^3/m pi (35/12)^2 dh/dt = 12 dh/dt = .449 ft/min

*January 4, 2017*

**Pre calc**

Good, you have two different ways now :)

*January 4, 2017*

**Pre calc**

slope = (20-13)/(4-3) = 7 also for any (x,y) slope = (y-20)/(x-4) so 7 = (y-20)/(x-4) 7 x - 28 = y - 20 so y = 7 x -8

*January 4, 2017*

**THANK YOU DAMON**

You are welcome :)

*January 4, 2017*

**Social Studies**

a.They conquered inland kingdoms, which they turned into a trading empire. --------------- The big advantage the Portuguese had over Arabs etc in the Indian Ocean was big ships with big guns. They did not try to march inland. India was a civilized country with real armies, not...

*January 4, 2017*

**Social Studies**

Yes, maybe b then c

*January 4, 2017*

**Social Studies**

It was particularly the various competing Christian missionaries that made the Japanese mad, and they were very angry about what happened in the Phillippines. The Dutch were allowed to hang out in a Nagasaki trading post because they did not try to convert people or push them ...

*January 4, 2017*

**Social Studies**

Particularly this excerpt: "Japan had been closed to the outside world for 250 years. When foreign people entered Japanese waters, even if they were shipwrecked by accident, they were interned in jails and some of them were killed (Lubor 33). The reasons for the Japanese ...

*January 4, 2017*

**Social Studies**

Ah yes, this is short and sweet http://willamette.edu/~rloftus/perry.html

*January 4, 2017*

**Social Studies**

I am looking for a link for question 2

*January 4, 2017*

**Social Studies**

no, no

*January 4, 2017*

**Social Studies**

Now for question 2, perhaps we better look at the start of American-Japanese relations. Did you read about only the Dutch being allowed there before that fleet arrived?

*January 4, 2017*

**Social Studies**

here is a wiki for Goa: http://www.google.com/search?q=goa+india&ie=utf-8&oe=utf-8

*January 4, 2017*

**Social Studies**

Well, I suppose I could give you some link to a wiki or something, but first think about it. The Portuguese ended it all in India long this after with Goa. Can you imagine a little country like Portugal marching around India ? They were sea farers

*January 4, 2017*

**Social Studies**

In question 1, remember we are talking about the Portuguese, not some tea company.

*January 4, 2017*

**Social Studies**

Ah, what do you think? The answer to question 2 is petty dramatic and amazing.

*January 4, 2017*

**Pre calc**

y = m x + b y = -(3/2) x +3/4 or 4 y = -6 x + 3

*January 4, 2017*

**History**

Well, my choices would be: 1. Prince Henry the Navigator, Bartolomeu Dias, Vasco da Gama .... so D 2.I would say B 3. See question 1.

*January 4, 2017*

**Math**

65*50 = 6500/2 = 3250 ft^2 so 1625/3250 $/ft^2

*January 4, 2017*

**American Government**

County responsibility is now chiefly law enforcement (sheriff and county jail) and registry of deeds and such. However it still exists and the towns and cities have not take over all county responsibilities.

*January 4, 2017*

**American Government**

Although our ounty government has been largely eliminated over the last decade, we still have a sheriff etc. Our town governments operate much like our city governments, although often having a Board of Selectmen instead of a City Council. Both towns and cities are often run ...

*January 4, 2017*

**American Government**

http://en.wikipedia.org/wiki/Essex_County,_Massachusetts

*January 4, 2017*

**Physics**

I think it is a dip and v^2/R = 0.15*9.81

*December 30, 2016*

**Physics**

density = 1000 kg/m^3 is easier :) You do not say if you want gage pressure or absolute pressure I will assume gage rho g h = 1000*10*25 =2.5 *10^5 Pascals or N/m^2 if you want absolute pressure add one atmophere or about 1*10^5 for a total of 3.5*10^5 Pascals

*December 30, 2016*

**Physics**

You already said the speed of the boat through the water was 2 m/s The speed over the land is 2-.8 = 1.2 m/s

*December 30, 2016*

**physics**

v^2/R = g or it loses contact m g(h-D) = .5 mv^2 v^2 = g R = .5 g D so m g(h-D) = .5 m *.5 g D =.25 mgD h-D = .25 D h = 1.25 D

*December 30, 2016*

**Math**

anything^0 = 1 so x^3/x^3 = x^0 = 1 y^6/y^6 = y^0 = 1 so 1

*December 29, 2016*

**asthmatics**

assuming it is the height that is 9.5 outside volume = 23 * 15.5 * 11 inside volume = 20 * 12.5 *9.5 now subtract the inside from the outside

*December 29, 2016*

**maths**

Thank you rabin for entertaining the math tutors :)

*December 29, 2016*

**Chemistry**

(750-726)/(20-10) = 2.4 (800-750)/(40-20) = 2.5 (880-800)/(70-40) = 2.7 (960-880)/(100-70)= 2.7 slope increasing a bit but 2.7 seems a reasonable guess slope = (x-960)/(150-100) (x-960)= 50(2.7) x = 960 + 135 = 1095

*December 28, 2016*

**calculus**

http://www.mathsisfun.com/calculus/differential-equations-homogeneous.html LOOK at the example at the end :)

*December 28, 2016*

**Physics**

This might help: http://www.slideshare.net/ahmedqadoury/periodic-and-aperiodic-sounds-2

*December 28, 2016*

**Physics**

I am sorry I can not because if you do a Fourier transform on even a spike you can express even an impulse as a sum of periodic signals. However there are articles on non-periodic vibrations in the technical literature. I question if they are really that but anyway take a look...

*December 28, 2016*

**math, algebra**

120 + 7 x = 11 x so 4 x = 120 x = 30

*December 28, 2016*

**Matt**

2.54 cm/in L in cm = L in inches (2.54 cm/in) so 2.54 times as many centimeters as inchess

*December 28, 2016*

**Science**

MASS IS CONSERVED! Until you get to Einstein and Special relativity, the total mass is CONSTANT. .015 + .050 = .065 kg

*December 28, 2016*

**Math**

time = t vf t = 260 vp t = 320 so 260/vf = 320/(vf+15) 320 vf = 260 vf +260(15) 60 vf = 390 3 vf = 39 vf = 13 km/hour

*December 28, 2016*

**SAT Math Question?**

L --- 1/3 job/hr S ---1/5 job/hr together 1/3 + 1/5 = 8/15 job/hr (8/15 j/h)(1 h) = 8/15 job done that leaves (15-8)/15 = 7/15 to do (1/5)job/hr * t = 7/15 job t = 35/15 hr for S to finish 35/15 hr * 60 min/hr = 140 min

*December 28, 2016*

**algebra**

3j(j^2-17j +70) =3j (j-10)(j-7)

*December 26, 2016*

**algebra**

9 r^2 - 30 r + 25 = 0 (3 r -5)(3r-5) = 0 r = 5/3 and 5/3 repeated, parabola just touches r axis

*December 26, 2016*

**algebra**

2(2a^2-5a+3) is 2(2a-3)(a-1)

*December 26, 2016*

**algebra**

64 z^2 - 1 That is the difference of two squares remember a^2-b^2 = (a-b)(a+b) so (8z-1)(8z+1)

*December 26, 2016*

**nobody knows**

Did you try to copy and paste? That does not work.

*December 26, 2016*

**physics**

Assuming that they are in series, 1.2 amps goes through each so current density = 1.2 /(pi d^2/4) for each

*December 26, 2016*

**calculus too hard**

Use Steve's solution if no typos in problem statement.

*December 26, 2016*

**calculus too hard**

I am still not sure it is right maybe dx/dt = k(a-t) ?? if so try x = c + p t - kt^2/2 then dx/dt = p -kt then p = ka and if c = 0 then dx/dt = 0 +ka -kt = k(a-t) so then x = ka t - k t^2/2

*December 26, 2016*

**typos?**

I think you might mean dx/dt = k(a-x) but what is c?

*December 26, 2016*

**Maths**

tan 60 = X1/1 tan 30 = X2/1 d = X2 - X1 v = d/t t in hours = 10 s /(3600 s/hour)

*December 25, 2016*

**math**

angles OBA and OCA are right angle BOC is 90-40 = 50 ABC =180 - 20 - 90 = 70 = ACB

*December 25, 2016*

**Maths**

1.12 p = 15,000

*December 25, 2016*

**Calculus 3**

No, because multiply by sqrt 14 which is |n|

*December 25, 2016*

**Calculus 3**

n = 3 i +2 j + k we want F dot n = |F| |n| cos angle but we are given that |F| cos angle is 3 z/sqrt14 so what is |n|? sqrt (9+4+1) = sqrt 14 ha, that helps :) so F dot n = 3 z so do the integral of 3 z over the surface

*December 25, 2016*

**Calculus 3**

http://tutorial.math.lamar.edu/Classes/CalcIII/SurfIntVectorField.aspx boundary in first quadrant means x from 0 to 2 and y from 0 to 3 (sketch that thing)

*December 25, 2016*

**math**

89/18 =4 + something 4 * 18 = 72 89 -72 = 17 left over

*December 25, 2016*

**Physics**

well, sure the tension does work, but the idea is that you do not have to get into the innards of this system because its kinetic energy is described by the (1/2)(m1+m1)v^2 and (1/2) I omega^2 and its potential energy by the m g h of the two objects. You could solve the whole ...

*December 24, 2016*

**sorry, read -1 not -3**

-3(-2) = +6

*December 24, 2016*

**MATH**

y = -1 x +42 slope = -1 = change in y/change in x if change in x - -1 then change in y /-2 = -1 so change in y = -1 (-2) = +2

*December 24, 2016*

**Physics**

max ke = max Pe = m g h h = r (1-cos 60) = r/2 so max (1/2) m v^2 = m g r/2 max v^2 = g r T = m g + m v^2/r T = m (g + g) = 2 m g = 2(.05)(10) T = 1 Newton

*December 24, 2016*

**physics**

4 *10 = 40*v v = 1

*December 24, 2016*

**Physics**

q = c v same q on each v1+v2 = 100 q/c1 +q/c2 = 100 q/4 + q/2 = 100 3 q/4 = 100 q =400/3 on each now same v on each and total charge=800/3 and total c = 6 v = q/c = 800/18 = 44.4 volts

*December 24, 2016*

**algebra**

let's see we need 5*5-1 in the middle something of form (5c ) ( 5) (5c-1) (c +5)NO that gives +24, we want - (5c+1)(c-5) = 5c^2 -24c -5 progress so (5c+d)(c-5d) = 5c^2 -24cd -5d^2 done

*December 23, 2016*

**physics**

Ac = g there = v^2/R = omega^2 R omega = 2 pi radians/24 hours =2 pi radians /(24*3600)seconds R is given so find omega^2 R

*December 23, 2016*

**Specialist Mathematics**

|x+y| two possibilities A: x+y B: -x-y = -(x+y) if A: x+y is maximum when both are + then x+y = |x|+|y| if B: -(x+y) has same absolute value as A etc

*December 22, 2016*

**History -**

I think I might have picked C because some of them are in South America and Asia and the Middle East.

*December 22, 2016*

**Linear Relations MATHS**

You are welcome

*December 22, 2016*