Sunday

September 25, 2016
Total # Posts: 27,151

**maths**

5(x+iy)(x-iy)+3(x+iy -x +iy) =42-15i 5x^2+5y^2 + 6iy = 42-15i 5 x^2 + 5 y^2 = 42 6 i y = -15i y = -15/6 5 x^2 + 5 (225/36) = 42

*September 25, 2016*

**Physics**

kinetic energy at planet surface = potential energy at max height (1/2) m v^2 = m g h h = v^2/2g so if g is g earth/6 then the height is h earth * 6

*September 24, 2016*

**Science**

http://www.jiskha.com/display.cgi?id=1474739216

*September 24, 2016*

**Math**

combinations of 9 taken 3 at a time = 9!/[ (9-3)!(3!)] = 9*8*7/(3*2) = 3*4*7 = 12*7 = 84

*September 23, 2016*

**Physics**

g force down slope = mg sin phi friction force up slope = mu mg cos phi a = F/m = g sin phi - mu g cos phi = g (sin phi - mu cos phi)

*September 23, 2016*

**Physics**

To raise something to a power please use ^ symbol To divide please use / symbol work done = kinetic energy gained = (1/2)mv^2 power = work done/time = (1/2) m v^2 t = m v^2 /(2t)

*September 23, 2016*

**Physics**

average speed = .568/2 = .284 m/s time = t = .389/.284 = 1.37 seconds a = change in speed / change in time = .568/1.37 = .415 m/s^2 F = m a = 79.5*.415 = 33 Newtons

*September 23, 2016*

**Physics**

Well, yes but it was the change in POTENTIAL energy m g h. The velocity is assumed negligible.

*September 23, 2016*

**Physics**

400*9.81 = 3924 Newton weight I guess the mechanic is also on the ground?mechanical advantage needed = 3924/250 = 15.7 since pulleys do not come in fractions we will need 16 times 16*3 = 48 meters

*September 23, 2016*

**Physics**

+i +j +k -5 -3 -4 +0 +1 +0 = 5 k + 4 i or 4i +0j +5k (note obviously perpendicular to j so no j component)

*September 23, 2016*

**Social studies**

I would claim horses. Try: http://latinamericanhistory.about.com/od/theconquest/a/09armsconquest.htm

*September 23, 2016*

**Social Studies**

no, please read what I said.

*September 23, 2016*

**Social Studies**

Native to Brazil. Portuguese brought it to West Africa.

*September 23, 2016*

**Engineering Math**

x = Xi e^-kt .41 = e^-120k ln.41 = -120 k k = .00743 .5 = e^-.00743 t ln.5 = -.00743 t t= 93.3 daya so I pretty much agree with you .77 = e^-.00743 t t = 35.2 days

*September 23, 2016*

**Math**

You are welcome.

*September 23, 2016*

**Math**

|-13| = +13 which is not -13

*September 23, 2016*

**Social studies NEED HELP**

What does your book say? Does it discuss the Portuguese going east around Africa to the Indian Ocean and East Indies? Does it mention that other European countries might want to find another way to get there and that Columbus thought he could get to the East Indies by sailing ...

*September 23, 2016*

**algebra**

a + (n-1)d .5 + (n-1).5

*September 23, 2016*

**algebra**

http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html

*September 23, 2016*

**algebra**

.5 , 1 , 1.5 , 2.0 , 2.5 is .5 , 1.5 3.0 , 5.0, 7.5 on day 5 of course this is an arithmetic sequence with d = .5

*September 23, 2016*

**physics**

assume you mean 10^7 and 10^-16 etc How long to move 35*10^-3 m ? t = 35*10^-3/1.9*10^7 so t = 18.4 * 10^-10 seconds a = F/m = 6*10^-16 / 9.11*10^-31 = .659 * 10^15 m/s^2 d = (1/2) a t^2 = (1/2)(.659*10^15)(339*10^-20) = 112*10^-5 = .00112 meters or 1.12 mm

*September 23, 2016*

**Math**

n-1 , n , n+1 4(n-1)-13 = n+1 4 n - 4 - 13 = n+1 3 n = 18 n = 6 5, 6, 7

*September 23, 2016*

**Social Studys**

How about "no taxation without representation" ?

*September 21, 2016*

**jay**

P/2 = L+w w = P/2 - L

*September 21, 2016*

**jay**

A = h (a+b)/2 2 A/h = a + b a = 2A/h - b

*September 21, 2016*

**equation is wrong !**

h(a+b)/2 not times 2 average base times height, common sense

*September 21, 2016*

**Math**

use 4y-6 for x y = 4 - 3 (4y-6) y = 4 - 12 y + 18 13 y = 22 y = 22/13 x = 4(22/13) - 6 x = 88/13 - 78/13 x = 10/13

*September 21, 2016*

**Math**

I think you mean 12 grams and 40% 12 = .4 x so x = 12/.4

*September 21, 2016*

**Science**

How about mountain ranges for example ?

*September 21, 2016*

**Algebra**

I knew the slope m so I used y = m x + b I put in 2 for x and -3 for y that is the point (2,-3) -3 = (1/3)(2) + b

*September 21, 2016*

**Algebra**

slope = m = (-4+3)/(-1-2) = -1/-3 = 1/3 -3 = (1/3)(2) + b b = -9/3 - 2/3 = -11/3 y = (1/3) x -11/3 3 y = x - 11 x -3 y = 11

*September 21, 2016*

**PHYSICS**

yf = yo + vo t + (1/2) a t^2 yf = 0 yo = unknown vo = 0 (dropped not thrown) vf irrelevant ( = a t) a = -4.9 indeed t = 3.5 so 0 = yo + 0 -4.9 (3.5)^2 or yo = 4.9 (3.5)^2

*September 21, 2016*

**statistics**

http://davidmlane.com/hyperstat/z_table.html

*September 21, 2016*

**Science**

Huh? v = a t so a = 15/10 = 1.5 m/s^2 not 2.5 m/s^2 Something is wrong with the problem statement.

*September 20, 2016*

**Math**

(4 km/cm)(4 cm) = 16 km

*September 20, 2016*

**science**

water is neutral lime juice and HCl are acidic NaOH is basic

*September 20, 2016*

**Chemistry**

What do you think? Imagine doing this and measuring how much is in the beaker by the lines on the side.

*September 20, 2016*

**physic**

so the increase in speed of the dropped one cancels the slow down of the other and height = initial speed up * time = 20*3 = 60

*September 20, 2016*

**World History**

I would say the competent leadership, perhaps B

*September 19, 2016*

**science**

m g = 200 * 5 Newtons work = PE = m g h = 200 * 5 * 1 Joules work/time=power = 200 * 5 * 1 / 100 Joules/second or Watts

*September 19, 2016*

**Algebra**

well, I think I would multiply the first one by three and the second one by two 15 x + 12 y = -42 6 x + 12 y = 12 ------------------ subtract 9 x = -54 or x = -6 then -18 + 6 y = 6 6 y = 24 y = 4 (-6 , 4 )

*September 19, 2016*

**Influential Ideas and Events Quiz( Check Answers)**

Those were my choices as opposed to your choices. The First Amendment one I feel strongly about though :) The Bill of Rights starts off with freedom of speech, the very first thing.

*September 19, 2016*

**my guesses**

d) people who live together under a sovereign government c) It mediates conflicts and supports international projects b) self-reliance c) The leader of Britain is chosen by the legislature (Parliament) (Prime Minister) First Amendment!!!! Congress will make no law abridging ...

*September 19, 2016*

**math**

4 c + 2 h = 78 c+h = 35 so 2h = 70-2c 4 c + 70 - 2c = 78 2 c = 8 c = 4 35 - 4 = 31 hens

*September 19, 2016*

**Algebra 2**

fifth root of n = n^(1/5)

*September 19, 2016*

**Algebra 2**

x^(3/5) i^2 = -1 i^3 = -i i^4 = 1 i^5 = i i^6 = -1 i^7 = -i i^8 = 1 note pattern i^64 = 1 and i^63 = -i

*September 19, 2016*

**physics**

the center of gravity moves up 1.5 meters m g h = 20 * 9.81 * 1.5

*September 19, 2016*

**maths help me**

energy/second: mgh + (1/2) m v^2 where m = mass/second what is mass/second? m = 1000 kg/m^3 * pi (.05^2)m^2 * 50 m/s

*September 19, 2016*

**physics**

1000 * 9.81 * Vol = 25-15 = 10 N so Vol is about .001 m^3 25/.001 = 25,000 N/m^3 or about 2500 kg/m^3 or about 2.5 times that of water

*September 19, 2016*

**Physics**

h = 20 t - 4.9 t^2 15 = 20 t -4.9 t^2 4.9 t^2 -20 t + 15 = 0 solve quadratic for two values of t little t on the way up big t on the way down

*September 18, 2016*

**Physics**

acceleration F = m A dF/dt = m dA/dt (unless the mass changes:)

*September 18, 2016*

**Maths**

2 km + (3/8)j + (1/2)j = 1 j 2km = (8/8 - 4/8 - 3/8)j 2 km = j/8 j = 16 km total you do the rest now :)

*September 18, 2016*

**Math**

n + n+1 = 2n + 1 2n is even the next one is odd :)

*September 18, 2016*

**Math**

.41 L + .21 (8-L)= 2.08 .41 L + 1.68 - .21 L = 2.08 .20 L = .40 L = 2 p = 8-L = 6

*September 18, 2016*

**Math**

x-4 + x-2 + x + x+2 + x+4 = 50 5 x = 50 x = 10

*September 18, 2016*

**Math**

n-2 + n + n+2 = 3 n which you can divide by 3 :) It does not matter that they are odd

*September 18, 2016*

**Use parentheses**

I do not know what you mean x^3 + 1/(1/x^3) or what you said which is x^3 + 1 + 1/x^3 ???? if the first multiply top and bottom of second term by x^3 x^3 + x^3/1 = 2x^3

*September 18, 2016*

**whoops, go with Reiny**

I missed that this is a binomial distribution problem. The combinations are not equally likely.

*September 18, 2016*

**Math**

easier grid for me h -> 0 1 2 3 4 t -> 4 3 2 1 0 I see five possible outcomes of which 2 work so I get 2/5 HHTT is the same here as TTHH or HTTH

*September 18, 2016*

**Physical Science**

work = force * distance in direction of force 310 = force * 1.5 force = 310 J/1.5 m = 207 Newtons

*September 18, 2016*

**Math**

10 a + 5 s = 1700 so s = 340 - 2 a s+a = 270 340 - 2a + a = 270 a = 340-270 a = 70

*September 18, 2016*

**Physics**

v = a t = 2.46 t x = -10 + (1.23) t^2

*September 18, 2016*

**Math**

15 + .25 t = 20 +.05 t .20 t = 5 t = 25

*September 18, 2016*

**science**

4*12+10 = 58 grams/mol 14.17/58 = .244 mol 2C4H10 + 13 O2 ---> 10H2O + 8 CO2 mols CO2 produced = .244(8/2)=.977 mol 2*12+16 = 40 grams/mol 40 g/mol * .977 mol = 39.1 grams

*September 18, 2016*

**Math**

t = 4 c t+c = 360 5 c= 360 c = 72 t = 288

*September 18, 2016*

**calculus and chemistry**

T = Ts + (To-Ts)e^-(kt) Ts = T surrounding = 10 To = initial T = 160 60 = 10 +(150)e^-(5k) e^-(5k) = .333333 -5k = -1.1 k = .22 so 20 = 10 + 150 e^-.22t e^-.22 t = .0666666 .22t = 2.71 t = 12.3 min 12.3 - 5 = 7.3 min more

*September 18, 2016*

**Maths**

r = triangle leg = 20 so is the base 20 so equilateral so 60/360 = 1/6 of circle (1/6)2 pi r =(1/3)pi 20 = 20.94 cm

*September 18, 2016*

**Physics**

work done = loss of ke = (1/2)m v^2 = 1000*625 Joules power = work/second = 1000 * 625 / 5 Watts

*September 18, 2016*

**Integrated Math**

correct

*September 18, 2016*

**messed up link**

http://en.wikipedia.org/wiki/Galileo%27s_Leaning_Tower_of_Pisa_experiment

*September 18, 2016*

**physics**

The weight does not matter (Google Galileo, http://en.wikipedia.org/wiki/Galileo%27s_Leaning_Tower_of_Pisa_experiment) about 9.81 m/s^2

*September 18, 2016*

**scince**

10 log base ten of power ratio or in this case 10 log 20 about 13 dB If by "intensity" the question means amplitude rather than power then it is 20 log or about 26 dB

*September 18, 2016*

**Physics**

http://www.bbc.com/news/business-27021610

*September 17, 2016*

**Physics**

a = change in velocity/change in time = (-10 - 10)/5 = -20/5 = -4 m/s^2 v = vi + a t at t = 2 v = 10 -4*2 = 2 m/s at t = 3 v = 10 -4*3 = -2 m/s

*September 17, 2016*

**PRE-CAL**

yes, about 55 years 10% doubles in about 7 years :)

*September 17, 2016*

**Physics (Mechanics)**

straight up I guess (1/2) m v^2 = m g h h = 22^2/(2*9.81) total height = .8 + h

*September 17, 2016*

**physics**

m g h = 5.2 * 9.81 * 3.1 Joules

*September 17, 2016*

**physics**

(12)(15)(8.7)^2

*September 17, 2016*

**physics**

m g h

*September 17, 2016*

**physics**

W = F d 307 = F (1.1)

*September 17, 2016*

**Science**

500 *4 = fulcrum force * 1.5 fulcrum force = 500 *4/1.5 force up = fulcrum force force down = 500 + bolt force- so bolt force = fulcrum force - 500

*September 17, 2016*

**linear programming**

Oh, forgot the y<8 constraint

*September 16, 2016*

**I did one yesterday**

I did one of these for him yesterday.

*September 16, 2016*

**HISTORY**

Meanwhile I am wondering if the slaves bought one way or round trip tickets.

*September 16, 2016*

**What are your answers ?**

I bet you can get some of these if you really try. Post your answers and if you are wrong I suspect you will hear about it.

*September 16, 2016*

**Social Studies**

I disagree.

*September 16, 2016*

**linear programming**

well do it. graph the two lines in the first quadrant. y = -(5/9)x + 10 must be above and right points (0,10) and (18,0) y = -(9/8)x + 18 must be below and left points (0,18) and (16,0) intersection at (72*8/41 , -64*5/41 + 10) which is about (14,2) at 0,18 --> 126 at (14,2...

*September 16, 2016*

**Math**

8 (50 +4) = 8*50 + 8*4 = 400 + 32 = 432

*September 15, 2016*

**Math, number and operations base**

8*1000 + 5*100 + 17*10 + 12 *1 = 8*1000 + 5*100 + 1*100 +7 *10 + 1*10 + 2 = 8*000 + 6*100 +8*10 + 2 = 8682 agree :)

*September 15, 2016*

**Please help with Algebra 2 Ms. Sue**

sure, why not slope AB = -2/-6 = 1/3 slope AC = -8/-4 = 2 slope BC = -6/2 = - 3 oh! AB is perpendicular to BC ! slope AB = -1/slope BC

*September 15, 2016*

**maths need help**

http://www.wolframalpha.com/input/?i=derivative+x%5E(e%5E3x)%5Ex+

*September 15, 2016*

**need to know takeoff speed**

Then use conservation of momentum

*September 15, 2016*

**Linear Algebra**

let A be on x axis = a i + 0 j then B put on y axis = 0 i + b j (b could be - of course) ||A + cB|| = || sqrt(a^2 + c^2b^2 || which is >/= sqrt a^2

*September 15, 2016*

**physics**

t = time = distance/speed = 15.2/41.3 drop = (1/2)g t^2 = 4.9 t^2

*September 14, 2016*

**Physics**

c = 3*10*8 m/s seconds/yr =3600 s/h * 24h/day * 365days/yr

*September 14, 2016*

**algebra**

2 x + 4 x + 5 x = 44 11 x = 44 x = 4 2 x = 8 etc

*September 14, 2016*

**TYPO**

b/g = 3/4 now 3 boys/7 total is again 3 boys/4 girls the schools have the same number of girls, boys and totals.

*September 14, 2016*

**Math**

b/g = 3/4 now 3 boys/7 girls is again 3 boys/4 girls the schools have the same number of girls, boys and totals.

*September 14, 2016*

**math**

7/1 5/2 8/10

*September 14, 2016*

**Geometry**

You are welcome.

*September 12, 2016*