Wednesday

July 23, 2014

July 23, 2014

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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