Wednesday
July 23, 2014

Posts by steve


Total # Posts: 23,930

geometry - oops
I misread 1008 as 1080. Go with Reiny.

geometry
720 = 2^4 * 3^2 * 5 1080 = 2^3 * 3^3 * 5 672 = 2^5 * 3 * 7 So, the largest number that evenly divides all of those is 2^3 * 3 = 24

algebra
x+y=15 8x+5y=96 now just solve for x and y

Math
150 is less than the mean for Natalia's class. So, if that score is removed, the mean rises. Similarly, since 150 is greater than the mean for Eric's class, if that score is added, the mean rises.

Math
y = x^2 + 3x + 1/4 = x^2 + 3x + (3/2)^2 + 1/4 - (3/2)^2 = (x + 3/2)^2 - 2 That should answer most of your questions.

Math
30x+20y+10z = 800000 x+y+z = 40000 x = y/2 x=10,000 y=20,000 z=10,000

algebra 1
If we model the situation as y = mx+b then we have 120m+b = 18 300m+b = 6 Subtract to get -180m = 12 m = -1/15 So, b = 26 y = -1/15 x + 26 y=0 when x = 390

finite math
Hmm. Looks like 0.438

finite math - PS
That's the experimental probability. The theoretical probability is still 1/2.

finite math (probability
I'd say 57/100

math
400m+b = 2150 300m+b = 1650 subtract to get 100m = 500 m = 5 so, b = 150 y = 5x+150

physics
given the drawing as shown below, I calculate 3.62 km at 46°

geometry
Assuming the chords are parallel, think of 8-15-17 right triangles.

Science
Seems to me that the only possible reason can be that ice provides less friction, whatever the underlying properties. Friction translates into a restraining force, reducing the speed.

science
F = ma, so 20 = 4m m = 5 kg

math
what a lot of noise. Distance traveled: 128100 ft = 24.26 mi Average speed: 335.92 mi/hr so, time falling is 24.26mi / 335.92mi/hr = 0.0722hr = 4.3 minutes

chemistry
1000cm^3 * 13.6g/cm^3 * 1mole/200.59g = 67.8 moles

chemistry
.09g * 1mole/18g * 6.02*10^23mol/mole = 3.01*10^21 molecules

chemistry
just plug in the mol wts of the compounds in 0.78*N2 + 0.21*O2 + 0.009*Ar * 0.001*CO2

algebra
the ratio is 6:6, making 12 total. 48 = 12*4, so 24:24 will satisfy everyone.

Geometry
figure the length and slope of AB and CD. If they match, it's a ||-ogram.

Geometry
well, what are the diagonals? AC and BD midpoint of AC = (-1/2,-2) midpoint of BD = (-1/2,-2) Looks like the diagonals bisect each other.

projectile motion
we know that the path follows x(t) = v cosθ t y(t) = 160 + v sinθ t - 4.9t^2 I will assume that the cliff and the tower are the same, otherwise I'm confused. x(20) = 1800 y(20) = 0 So, 20v cosθ = 1800 20v sinθ = 1800 Clearly θ = π/4 and v = 12...

Algebra
no solution the lines are parallel, and so do not intersect.

Algebra
see the solution at http://www.wolframalpha.com/input/?i=solve+4y%3Dx%2B4%2C+x%3D2%2F3y%2B8%2F3+

Physics
150km/2.5hr = 60km/hr 150km/2.0hr = 75km/hr velocities is the same, but directed. 300km/4.5hr = 66.67km/hr avg velocity is 0, since no net distance was traveled.

Physics
4 hr * 300km/hr = 1200km 2.5 hr * 400km/hr = 1000km 2200km/6.5hr = 338.46km/hr

Math: Trig
since cos pi/3 = 1/2, sec pi/3 = 2 But, arcsec has principal values from 0 to pi, so arcsec(-2) = pi - pi/3 = 2pi/3. Note: Some authors define the range of arcsecant to be ( 0 ≤ x < π/2 or π ≤ x < 3π/2 ), because the tangent function is nonnega...

MATH
No idea. Do it the way I did, but you have to use integration by parts. If you get stuck, show how far you got. You should wind up with -(x+1)e^-x for x<0 (x-1)e^x for x>=0

MATH
since |x| = -x for x < 0. ∫[-∞,x] e^-|t| dt = ∫[-∞,x] e^t dt if x < 0 = e^t So, for x>=0, ∫[-∞,x] e^-|t| dt = ∫[-∞,0] e^t dt + ∫[0,x] e^-t dt = 1 + (1-e^-x) = 2 - e^-x

maths
32 is 2^5 so, 1/32 = 1/2^5 = 2^-5

Math - incomplete
did you want some particular value for x?

Calculus
Note that you have ∫1/(x^2 − 2x + 8)^(3/2) dx = ∫1/((x-1)^2 + 7)^(3/2) dx If x-1 = √7 tanu (x-1)^2 + 7 = 7 sec^2 u dx = √7 sec^2 u du and you have ∫1/(√7 secu)^3 * √7 sec^2 u du = ∫ 1/7 cosu du = 1/7 sinu = 1/(7 csc u) = 1/...

pseudocode app
this kind of code is about as simple as it gets. I don't know what language you plan to use, but do a little google to see how others have performed the operations you desire. There are lots of code snippets on line.

pseudocode app
read price tax = price * 0.08 print price,tax

Dela ray Mkhatshwa j.s.s
Let AC and BD intersect at E. Note that AE = 3 Draw a vertical line which will contain AC. Mark point E by intersecting an arc of radius 3 from A to E. Construct the perpendicular at E to AC. That will contain BD. Draw an arc centered at A of radius 6, which will intersect the...

Arithmetic
since the ratio between terms is constant, (k+6)/(2k+3) = k/(k+6) (k+6)^2 = k(2k+3) k^2+12k+36 = 2k^2+3k k^2 - 9k - 36 = 0 (k-12)(k+3) = 0 k = 12 and the sequence is 27,18,12,... so the ratio is 2/3 and S = 27/(1/3) = 81

Science
you need 4m = 600

sci
ever been on a roller coaster? ever stuck your finger in a wall outlet?

algebra
If the larger monitor has width w, then its length is w+5. So, we have w(w+5)-80 = 70 w^2 + 5w - 150 = 0 (w+15)(w-10) = 0 ...

Math
or, you can avoid b altogether and go straight to the point-slope form of the line with slope 1/2: y-12 = 1/2 (x-10)

physics
total distance is 30m + 40m = 60m = 6000cm total time is 5s + 20*60s = 1205s avg speed is thus 6000/1205 = 4.98cm/s

science
Look, I'm Furiously Engaged!

Chemistry
Since the reaction is 2HNO3 + Ba(OH)2 -> Ba(NO3)2 + 2H2O It takes 2 moles of HNO3 to neutralize 1 mole of Ba(OH2) 2.5g Ba(OH)2 is 0.0146 moles So, you need 0.0292 moles of HNO3 0.0292M / 0.109M/L = 0.268L of acid.

maths
since θ is in QII and Ø is in QIII, tanθ = 3/-4 secØ = √5/-2 now go figure.

physics please help!!!!!!
You want to find where 30t - 4.9t^2 = 60 - 4.9(t-.5)^2 t = 2.34 now plug that in to find either height. Assuming you meant 60m above where the first mass started. Things are different if the second mass is dropped when the first mass is 60m below it. But I'm sure you can m...

Calculus
Your function becomes less unwieldy if you note that if you divide top and bottom by cosx, you have y = (1/2 sin2x)/(sinx+cosx) All those nasty sec^2 and stuff go away and you have 2nd: wolframalpha.com is your friend. Enter 2nd derivative sinx/(1+tanx) and it pops right up. I...

Calculus
From what I can decipher from your cryptic use use of arcana (like A, II DC, Nr, etc.) your reasoning appears sound. I have a bit of trouble distinguishing between II DC and second DC. If they are the same, how can you check the sign of second DC without calculating it? If y&#...

physics
depends on the size of the umbrella.

math
The height y(t) is given by y(t) = h + vt - 16t^2 h + v - 16 = 148 h + 2v - 64 = 272 So, h=-8 v=172 y(t) = -8 + 172t - 16t^2 y(6) = 448

algebra
Since the population grew by a factor of 1.64 over 8 years, we have p = 4.2 * 1.64^(t/8) Since 1.64 = e^0.49 (call it e^.5), we have p = 4.2 * e^(t/16)

math
23% of wages is 14204.80 SS tax is 7658.24 FICA tax is 1791.04 so, subtract all those from her gross. Or, note that the total taxes add up to 38.3%, so just subtract that amount. Or not. You never really did ask a question.

Precalc
An equation is not a function. However, the definition of a function is usually written as an equation, as in f(x) = 2e^x - 7 But, that's really just a definition. An equation is usually something you have to solve for a particular value. For example, you might have to sol...

calculus
Oops. The w(t) given above is the y-value of Janice's position. You also need to use the x-value, which I'm sure you can do.

calculus
If Janice is at (0,0) when t=0, then the wheel obeys w(t) = 20(1-cos(π/8 t)) The ball follows the parametric equations x(t) = -70 + 60cos60° t y(t) = 60sin60° t - 16t^2 I have no idea where point A is, but having the equations should make things amenable to solution.

maths
(x+y)/2 = 44 If x=12, then (12+y)/2 = 44 12+y = 88 y = 76

Algebra
we have x^2-2 where x <= 1 2x where x < 1 Not quite clear where you want to go with this. I suspect you really meant 2x where x < 1 x^2-2 where x >= 1 If so, then the graph is a line which stops at x=1, and a parabola from there on. There is a jump discontinuity at...

bearing and distance
Use the law of cosines. After t hours, the distance d between the vehicles is d^2 = (8t)^2 + (5t)^2 - 2(8t)(5t)cos70° because the angle between the bearings if 25+45 = 70° So, just plug in t=3 and solve for d. As for the bearing from q to p, just find the slope of the ...

math,bearing and distance
not sure what bearing "s30 degree of north" is.

Math
you can easily see that K = 18-C So, put that into the 2nd equation and you have 2(18-C)+4C = 50 36-2C+4C = 50 2C = 14 C = 7 So, K = 11

math
x^3+3x = x(x^2+3) = (a^2/3-a^-2/3)((a^2/3-a^-2/3)^2+3) = (a^2/3-a^-2/3)(a^4/3 + 1 + a^-4/3) Note we have the factorization of the difference of two cubes: = a^2 - a^-2

Another this math tho
ding ding -- we have a winner!

this math tho
well, does 3(-10)+54 = 18?

3 questions Math
Oops. The synthetic division site was http://www.mathportal.org/calculators/polynomials-solvers/synthetic-division-calculator.php

3 questions Math
#18 - did you try this at the syntehtic division site I gave you? You can see polynomial long division at calc101.com; click on the "long division" button. #19 If you meant 1/(2x + 14) - 9/(x + 7) = -6 then that's just 1/(2x+14) - 18/(2x+14) = -6 -17/(2x+14) = -6...

Algebra ll
take a visit to http://www.mathportal.org/calculators/polynomials-solvers/synthetic-division-calculator.php and enter your coefficients. It will show the calculation, and even explain it if needed. It's hard to do it here, due to browser formatting of html.

Algebra
just find when the two are equal: 16x+150 = -x^2+60x-10 x^2 - 44x + 160 = 0 (x-40)(x-4) = 0 Now the answer should be clear.

algerbra
try something like this: http://www.wolframalpha.com/input/?i=3x%2By+%3C%3D+5 you can type in many different things, and it will show you the solution

algebra 2
B(t) rose by 32

Algebra (Factoring)
2(x^4-5x^2-36) 2(x^2+4)(x^2-9) 2(x^2+4)(x-3)(x+3)

Algebra
x/5 = 40/1.6 x/150 = 1.6/40 solve for x

Math
99 action means 55 horror, for a total of 154 films in 7 days. That's 22 films/day on average.

geometry
Assuming the sun rises at 6 am and sets at 6 pm, then at 9 am it is 45° above the horizon. That means a 147cm person will cast a 147cm shadow.

science
total mass of H2SO4 is 98 So, figure the % mass of each of the elements: H2 = 2 S = 32 O4 = 64

Math
since √x is not real for x < 0, we need 5y+1 >= 0 y >= -1/5 3y-5 >= 0 y >= 5/3 So, we need y >= 5/3 for the domain Now proceed to solve: √(5y+1) - √(3y-5) = 2 5y+1 - 2√[(5y+1)(3y-5)] + 3y-5 = 4 8y - 8 = 2√[(5y+1)(3y-5)] (4y-4)^2 ...

maths
This is just a work problem in disguise. Together the cars must cover a distance. 1/x = 1/4 + 1/6 = 5/12 x = 12/5 Check. Say the distance is 120 miles In 2.4 hours, the car covers 2.4/4 = 0.6 the distance. In 2.4 hours, the van covers 2.4/6 = .4 the distance. ok

math
you can order n things in n! ways. 24! = 6.2 * 10^23

Math
v = pi r^2 h So, just plug in r=3.7m and h = 2.4m

MATH
as you know, the derivative of e^u = e^u u' So, ∫e^u du = e^u Here, u = -x, so du = -dx You thus have ∫e^u (-du) = -∫e^u du = -e^u = -e^-x

Algebra
no way to tell

Algebra
If the first takes x hours, 1/x + 1/(x+5) + 1/(3x) = 1/(9/4) x = 4 So, the 3 pipes require 4,9,12 hours.

Arithmetic
1/3 of the marbles are green. So, 1/3 of at least 54 are green. How many is that?

whole number
1219 - 32 - 24 = ?

Science(electric circuits)
hmmm. The current in each parallel path may be different. That's a pretty open question, with no context.

englewood
total income,state,city tax is 6% 6% of 215 = 12.90 So, total deductions are 15.16+29.33+12.90 = 57.39 Net income is thus 215.00-57.39 = $157.61 Who says we are not taxed enough?

science-chemistry
.00565*450 = 2.54g of NaCl So, how many moles is that?

Math
I'm having a little trouble visualizing the angles in question. If we label the boats A and B and the dock D, which angles are we talking about?

Intro to Algebra
the area of a trapezoid is (b+B)h/2. Since we have 4 trapezoids with bases 5 and 6, the total area is 4(5+6)h/2 = 22h ft^2 paint costs $10/33ft^2 = .3030 $/ft^2 cost of $40 means 132 ft^2 22h = 132, so h=6 ft

Math
8^m 3^m = 24^m 576 = 24^2, so 24^(2(m-4)) = 24^m 2(m-4) = m 2m-8 = m m = 8

math - ouch
Good catch, Reiny - I was a bit sloppy.

math
cos3x = cos2x we need 3(x+2m*pi) = 2(x+2n*pi) for some m and n. Some playing around will get you x = 0,2/5 pi, 4/5 pi or, in degrees, x = 0,144,288

math
Facts as presented: g+p+c = 100 21g+8p+3c=600 since c = 100-(g+p), 21g+8p+3(100-g-p) = 600 21g+8p+300-3g-3p = 600 18g+5p = 300 Since 5p = 300-18g, g must be a multiple of 5. But, since g is even, it must be 10,20,30,... If g=10, p=24 If g=20, 18g=360, so any number g>10 wil...

intro to computer
B - nothing is free

Math please help!!
just plug and chug, using the quotient rule (2^x ln2 - e^x)(2^x+e^x) - (2^x-e^x)(2^x ln2 + e^x) --------------------------------------------------------------- (2^x+e^x)^2 You can simplify that to 2^(x+1) e^x (ln2 - 1) / (2^x+e^x)^2

math
90ft * 7ft * (1/2 oz/ft^2) = 90*7*(1/2) oz Note how the ft^2 cancel out, just leaving oz in the result. Watch the units, and they will help you decide how to multiply or divide the ratios.

Geometry
The sides are a b=a+12 c=b+24 d=c+36 So, a+b+c+d = 136 a+b+c+c+36 = 136 a+b+2c = 100 a+b+2(b+24) = 100 a+b+2b+48 = 100 a+3b = 52 a+3(a+12) = 52 4a+36 = 52 4a = 16 a = 4 So, the sides are 4,16,40,76

Math
if the dept head makes x, then x + 3x = 290000 4x = 290000 x = 72500

Algebra
learn to recognize common Pythagorean triples in right triangles. The simplest is 3-4-5. This is just double that, or 6-8-10. The rope is 10 feet long. Or, you can do the algebra, using r^2 = 6^2+8^2 and solve for r.

hindi
सर्वाधिक लोकप्रिय में से एक था बकवास कविता का ल&#...

Math
C = 2πr, so r = C/2π A = πr^2 = π(C/2π)^2 = C^2/4π In this case, A = 16^2/12 = 21.3

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