Tuesday

February 21, 2017
Total # Posts: 29,370

**differential equation**

Oh, yes, the diff eq which everyone already knows the solution for da/dt = -ka da/a = - k dt ln a = -kt a = A e^-kt

*October 2, 2016*

**please type the whole problem**

How many after 2.5 ? x = Xi e^-kt x = 75 e^-2.5 k ln(x/75) = -2.5 k k = ln(x/75)/(-2.5) solve for k so ln .5 = -k t solve for t

*October 2, 2016*

**Physics**

m v^2/r

*October 1, 2016*

**Physics**

angle pushes car toward center, centripetal

*October 1, 2016*

**physics**

you do not say what the question is average rpm during stop = 1150 turns to stop = 1150 *2.9/60 original radians/s = 2300 revs/min*2 pi rad/rev *1min/60 s = 241 radians/s angular acceleration = -241/2.9 whatever

*October 1, 2016*

**Math**

10 x + 15 y = 2500 y = 195-x 10 x + 15(195-x) = 2500 10 x + 2925 - 15 x = 2500 5 x = 425 x = 85 y = 195-x = 110

*October 1, 2016*

**Math**

70*400 = 28,000

*October 1, 2016*

**Pre Cal help please!!**

given f(x) = { 2x^2 + 5 x < or equal to 2 3 - x^2 x > 2 What???? Perhaps you mean: given f(x) = 2 x^2 + 5 when x < or equal to 2 3 - x^2 when x > 2 if x is slightly bigger than 2 3 - 4 = -1 if x is slightly smaller than 2 OR if x is 2 then 2(4) + 5 = 8+5 = 13

*October 1, 2016*

**Physics**

24.5 x = 85.5(11.6-x)

*October 1, 2016*

**Physics**

I guess an intercontinental ballistic rocket is something "thrown over a large distance (on earth)" so 5. What a nutty question though :)

*October 1, 2016*

**maths**

(x^3+y^3)(x^3-y^3) (x^3+3x^2y+3xy^2+y^3)*(x^3-x^2y+3xy^2-y^3)

*October 1, 2016*

**Trigonometry**

in an hour he goes 1/24 of circumference (1/24)(2 pi *12,000/pi) = 24,000/24 = 1000

*October 1, 2016*

**Physics**

fast one takes t = 76/5.2 seconds slow one goes d = 2(76/5.2) so 76 - 2(76/5.2)

*October 1, 2016*

**simpson**

http://www.wolframalpha.com/input/?i=solve+dy+%3D+sin(x%5E2)+dx

*October 1, 2016*

**Physics**

Ac = v^2/r = 36/2 = 18 m/s^2 m F = M Ac = 51 *18 Newtons weight = 51 * 9.81 Newtons almost 2 g

*October 1, 2016*

**value**

change of momentum = .03*600 = 18 average speed = 300 time = .2/300 Force = change of momentum/change of time = 18 *300/.2 Newtons = 90*300 =27,000 agree

*October 1, 2016*

**maths sir-reiny help calculus**

Click on the step by step in Wolfram

*October 1, 2016*

**maths sir-reiny help calculus**

http://www.wolframalpha.com/input/?i=solve+x+y+dx+%3D+(x%5E2+-x+y+%2By%5E2)dy

*October 1, 2016*

**Algebra**

first scoop has 19 choices second has 18 choices cone has 3 choices 18*19*3

*October 1, 2016*

**Probability**

first ace 4/54 second ace 3/53 third ace 2/52 first king 4/51 second king 3/50 multiply them

*October 1, 2016*

**whoops**

30/54

*October 1, 2016*

**sorry**

30/54

*October 1, 2016*

**Math Help!**

7/54

*October 1, 2016*

**Science**

if near earth surface F = m g = 2.5 * 9.81 N and acceleration is g = 9.81 m/s^2 if at great distance r from earth center you need to do F = 2.5 G Mearth/r^2 so a = G Mearth/r^2

*October 1, 2016*

**math condense logs**

ln is log base e 3[ln x-2 ln(x^2+1)]+2 ln 5 ln a - ln b = ln (a/b) n ln x = ln x^n so 3 ln [ x/(x^2+1)^2] + ln 25 ln 25[ x/(x^2+1)^2]^3 so agree with Sam

*October 1, 2016*

**maths asap need help**

pi/6 = 30 degrees our lines go though a point 5 units along there from origin x = 5 cos 30 y = 5 sin 30 that 30 degree line has slope sin30/cos30 = .577 the perpendicular has slope -1/.577 = - 1.732 so line is of form y = -1.732 x + b now put in y = 5 sin 30 and x = 5 sin 30 ...

*October 1, 2016*

**Math**

1/4 of them seem to be rotten so 25

*October 1, 2016*

**algebra**

d = 16 t^2 at t = 6, d = 16*36 = 576 at t = 7, d = 16*49 = 784 784 - 576 = 208

*October 1, 2016*

**Physics**

half a period 14 t changes by pi say from 14t = 0 to 14t = pi or t = pi/14

*October 1, 2016*

**Math (Finding points of intersection)**

You are welcome.

*October 1, 2016*

**typo**

do you mean -x+y = 1 ????? so y=x+1 if so circle with center at (0,0) and radius 1 line through (0,1) and (-1,0) x^2 + (x+1)^2 = 1 x^2 + x^2 + 2 x + 1 = 1 2 x^2 + 2 x = 0 x(x+1) = 0 x = 0 or x = -1 line hits the circle at the x and y axis intersections

*October 1, 2016*

**I am having trouble with this homework question ,**

first add those up to see if they add to one Yes, they do so everyone has one of those 4 types THEREFORE probability not O = 1 - probability of O 1 - .53 = 0.47

*October 1, 2016*

**MATH HELP ASAP**

Just like the other one there are 7 females with A out of 75 students probability that student is female with A = 7/75 so probability not female with A = 1-7/75 = 0.907

*October 1, 2016*

**MATH 125 help**

Hey look, I just did the not a female with A. Now you do this one.

*October 1, 2016*

**Cards Probability**

7/13

*October 1, 2016*

**beats me**

I wish the math people would stay away from navigation. They are hopeless at distinguishing between bearing and heading and here they evidently think a boat moves with the wind like an airplane forgetting that the hull is in the water sort of like a car on a road in a ...

*October 1, 2016*

**PROBABILITY : M&M'S**

Randomly picking what Amanda, two reds and a green in three picks?

*September 30, 2016*

**question incomplete**

finish the sentence please

*September 30, 2016*

**PROBABILITY MATH HELP!!!!! DICE**

There are 6 sides 1,2,3,4,5,6 three of those are even 3/6 = 1/2 = 0.5

*September 30, 2016*

**Math**

17 - 33 = -16 wicked cold around zero Fahrenheit

*September 30, 2016*

**Algebra**

9. j-3=-7 A. j=-10 B. j=21 C. j=-4 D. j=4 🔹🔹🔹 NO!!!! add 3 to both sides, result negative

*September 30, 2016*

**Algebra**

5. 2/3x=6 A. x=9 B. x=4 C. x=18 D. x=12 🔹🔹🔹 NO, what on earth are you doing?

*September 30, 2016*

**Algebra**

4. -2c=-18 A. c=-9 B. c=-36 C.=9🔹🔹🔹 YES THIS TIME

*September 30, 2016*

**Algebra**

4. -2c=-18 A. c=-9🔹🔹🔹? B. c=-36 C. c=9 D. c=36 NO!!!!!!

*September 30, 2016*

**Social studies**

I agree.

*September 30, 2016*

**Maths,fractions**

(6/15 + 5/15 + 4/15)x = x looks like 15 to me. There is no smaller common denominator

*September 30, 2016*

**english**

Players usually kick or "head" none :) to their teammates on the field.

*September 30, 2016*

**Is it possible if you guys can check my algebra HW**

Yes, it is possible, but what did you do?

*September 30, 2016*

**Is it possible if you guys can check my algebra HW**

take x from bag 2 take 3x from bag 1 amount now in bag 2 = 100 - x amount now in bag 1 = 100 - 3x 100 - 3 x = (1/2)(100 - x) 200 - 6 x = 100 - x 5 x = 100 x = 20 so bag 1 = 100 - 3(20) = 40 bag 2 = 100 - 20 = 80

*September 30, 2016*

**Pre alg**

y = 3 x-11 x+y = 153 Is that what you mean? If so x + 3x-11 = 153 4 x = 164 x = 41 y= 112

*September 30, 2016*

**math**

ROFL !!!!! yes

*September 30, 2016*

**Spanish**

I am assuming the first one is asking what someone else is like, not "you" :)

*September 30, 2016*

**Spanish**

Even I can do the first one. it is not what is your name it is not how am I it is not how are you What are your answers?

*September 30, 2016*

**English**

trust or lack thereof is certainly a theme see http://study.com/academy/lesson/the-death-of-arthur-summary-themes-quiz.html

*September 30, 2016*

**Physics**

a = -.8 g v = 4 - .8(9.81) t at v = 0 t = 4/[.8*9.81)

*September 30, 2016*

**Advice and Consent**

In the United States the SENATE must approve treaties. The Supreme court can always find anything unconstitutional :) SEE: http://www.senate.gov/general/Features/Treaties_display.htm

*September 30, 2016*

**typo, Pascals**

Newtons/m^2 = Pascals

*September 30, 2016*

**Physics**

Vi = 30 sin 40 u = 30 cos 40 h = 0 + Vi t - 4.9 t^2 0 = 30 sin 40 t - 4.9 t^2 0 = t (30 sin 40 - 4.9 t) so t = 30 sin 40/4.9 for downrange time range = r = u t r = 30 cos 40 * 30 sin 40 /4.9 = 30^2 sin 80/9.8 so the first one :)

*September 29, 2016*

**History**

well B is just as unlikely as C :)

*September 29, 2016*

**typo**

5/9 * 4/8 = 20/72 = 5/18

*September 29, 2016*

**maths**

susan takes lemon then ann takes lemon: 5/9 * 4/8 = 20/72 = 5/13 susan takes orange then ann takes orange: 4/9 * 3/8 = 1/6 add them

*September 29, 2016*

**Math**

3 2/3 = 9/3 + 2/3 = 11/3 17/4 = 16/4 + 1/4 = 4 1/4

*September 29, 2016*

**math**

.02 * 30 = original amount of dry cucumber which does not change .11 x = .02 * 30

*September 29, 2016*

**Math hellppp!!**

You are welcome.

*September 29, 2016*

**Math hellppp!!**

I get your parentheses right (-12/3)*(-8+(-4)^2-6)+2 -4^2 = 16 -8+16-6 = 2 -12/3 = -4 -4* 2 = -8 -8 + 2 = -6

*September 29, 2016*

**Math**

so what is 5^3 ?

*September 29, 2016*

**Math**

96/2 = 48 48/2 = 24 24/2 = 12 12/2 = 6 6/2 = 3 so 3*2^5 what is 5*5*5 ?

*September 29, 2016*

**Math**

let y = f(t)/2.7 to make it easy y = 1.004^t ln y = t ln 1.004 = 0.00399 t e^ln y = y = e^.00399 t so f(t) = 2.7 y = 2.7 e^.00399 t

*September 29, 2016*

**Social Studies Religion**

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; ........ If it does not ring a bell, use Google :)

*September 29, 2016*

**History PLEASE CHECK MY WOrK**

I agree with you.

*September 29, 2016*

**History**

Portuguese owned Brazil. Brazil had manioc. Portuguese took it to Africa. A

*September 29, 2016*

**History**

still A Google manioc Portuguese Brazil

*September 29, 2016*

**CHECK MY ANSWERS American Government**

1. agree but this ignores alternate path through constitutional conventions. 2. I guess you are right but am tempted by the first choice. I agree with the others.

*September 29, 2016*

**Grammar**

....and then there is that subjunctive "would" .... :)

*September 29, 2016*

**History**

http://agron-www.agron.iastate.edu/Courses/agron212/Readings/Corn_history.htm by the way American tribes were so thinly spread out that even if every single person one died it would have been just a blip in global population

*September 29, 2016*

**History**

Yes A, like corn You are welcome.

*September 29, 2016*

**History**

Oh come on! Native Americans did not have gunpowder. The European invaders did. Both had bows and arrows and hatchets. The Spanish horses were their best weapon though. Of course blowguns were kind of unusual in 17 th century Europe but I am not sure that is what we are ...

*September 29, 2016*

**History**

B is nonsense. Native Americans did not work out as slaves even here in America. They revolted or died. That is why the European creeps started importing slaves from Africa.

*September 29, 2016*

**Maths**

twice 3.50 is 7.00

*September 29, 2016*

**algebra**

You are welcome.

*September 29, 2016*

**algebra**

well, I write that line under as >/= or </= It does not change your approach and is just like an equal sign. If it is there, leave it there in your answer. </= is leas than or equal >/= is greater than or equal

*September 29, 2016*

**algebra**

multiply both sides by 1/2 n > 7 multiply both sides by 5 n > 55 NOW if you multiply both sides by a NEGATIVE number, you turn the arrow around and shoot the other way. multiply by -1/3 and reverse direction y > 6

*September 29, 2016*

**math**

e^ix= cos x + i sin x so what we have here is 2 cos pi/4 + 2 i sin pi/4 conjugate is 2 cos pi/4 - 2 i sin pi/4 but cos pi/4 = .5 sqrt 2 and sin pi/4 = .5 sqrt 2 so sqrt 2 - i sqrt 2

*September 29, 2016*

**Typo in units?**

I do not believe your lengths. are they all in meters?

*September 29, 2016*

**Social Studies**

I agree with you. It hit small farmers in what was then the west hard paying by the gallon but big distillers in the east could pay a flat fee.

*September 29, 2016*

**Physics**

time = t distance in meters = 1,000*distance in km distance covered by cheetah = d distance covered by gazelle = d-70 d = 100,000 t d-70 = 80,000 t so 70 + 80,000 t = 100,000 t 20,000 t = 70 t = 7/2000 hours in seconds (3600 s/h) t in seconds = 7*3600/2000 = 12.6 seconds

*September 29, 2016*

**Algebra error repair**

What is the product of (–6.8)2? a. –13.6 b. 46.24*** c. –46.24 d. 13.6 ============================= Notation???? what you wrote was (-6.8)(2) which is -13.6 , a. (not d) if you meant to type (-6.8)^2 that is (-6.8)(-6.8) = 46.24

*September 28, 2016*

**Algebra**

4. YES!!!! 5. Yes !!! 6. yes !!! 7. yes 8. result is POSITIVE so d is wrong a and b are right

*September 28, 2016*

**Algebra**

3. 10/7 * 10/7 = 100/47 so 10/7

*September 28, 2016*

**Algebra**

2. + 14 look, -14 * -14 works but so does +14 * +14 by convention though the positive square root is used

*September 28, 2016*

**Algebra**

What is the product of (–6.8)2? a. –13.6 b. 46.24*** c. –46.24 d. 13.6 ============================= Notation???? what you wrote was (-6.8)(2) which is 13.6 , d. if you meant to type (-6.8)^2 that is (-6.8)(-6.8) = 46.24

*September 28, 2016*

**physics**

v = Vi + a t 23.4 = Vi + 8 t average speed = (Vi+23.4)/2 so t = 9.7/[ (Vi+23.4)/2 ] so 23.4 = Vi + 8*9.7/[ (Vi+23.4)/2 ] solve for Vi

*September 28, 2016*

**physics**

h = Hi + Vi t - 4.9 t^2 0 = Hi + 6.22(2.7) - 4.9 (2.7)^2

*September 28, 2016*

**science**

you mean 20 m/s^2 I think F = m a = .15 * 20 = 3 N

*September 28, 2016*

**maths /science**

v = -9.81 t = -25 so question 2 t = 25/9.81 question 1 d = -4.9 t^2

*September 28, 2016*

**maths/science**

just like the other one v = - g t -63.7 = -9.81 t

*September 28, 2016*

**maths**

let g = 9.81 m/s^2 then v = -gt = -9.81*7 m/s or if using clunky units g = 32 ft/s^2 v = -32*7 ft/s

*September 28, 2016*

**Math**

I do not know what "break apart" means. But if I did not already know the answer I would think 54 = 60 - 6 = 10*6 - 1*6 = (10-1)6 distributive property = 9 * 6 so 9

*September 28, 2016*

**Math**

-1 +6 -1 +6 -1 +6 so 20-1 = 19 19+6 = 25 25-1 = 24 24+6 = 30 etc

*September 28, 2016*

**Math**

(1/4)(2/3) = 2/12 = 1/6

*September 28, 2016*