Saturday

April 19, 2014

April 19, 2014

Total # Posts: 21,783

**math help**

Think of a regular hexagon. All the angles are 120°. Now, think of pressing down on the top, keeping the top and bottom sides parallel. The two side angles will decrease, and the other four angles will increase. Stop when the side angles have become acute.

**maths**

5^(logx) + x^(log5) = 50 Note that log(5^logx)) = logx * log5 log(x^log5)) = log5 * logx So, the two are equal. That means 2*5^logx = 50 5^logx = 25 = 5^2 logx = 2 x = b^2 where logs are base b. So, if natural logs, x = e^2 if common logs, x = 10^2 = 100 check (common logs): 5...

**College Math**

74 are taking something 36+52 = 88, so 14 are taking both. So, 22 are taking biology only 22/200 = .11 is P(biology only)

**MATH QUIZ PLS HELP!!!**

#6 baffles me. Pyramids don't have a radius. All the others look ok, as long as #5 wants the volume.

**MATH**

first step, as I have shown you on two of these, is do the substitution. Wherever there is an x, replace it with 789: -2.5(789^2) + 2825(789) - 115812.5 Now just pull out your handy calculator, or use an online calculator, and discover that the value is 556810

**Math - PreCalc (12th Grade)**

it asks for the first natural number ... the natural numbers are 1,2,3,... So, start trying them: n=1: (2n-1) = 1 1 <= 4*1-1 1 <= 3? yes n=2: (2n-1) = 3 1+3 <= 4*2-1 4 <= 7? yes n=3: (2n-1) = 5 1+3+5 <= 4*3-1 9 <= 11? yes n=4: (2n-1) = 7 1+3+5+7 <= 4*4-1 1...

**Math - PreCalc (12th Grade)**

start checking. How about showing some of your own ideas on further problems? I can do them - the goal is for you to work on them, eh?

**Math - PreCalc (12th Grade)**

Ummm. Do you not think it would be A? I explained how the discontinuity could be removed. Hence, it is removable.

**Math - PreCalc (12th Grade)**

at x=5, f(x) = 0/0, or undefined. At any other value, though, f(x) = (x-5)(x+5)/(x-5) = x+5 So, f(x) is undefined only at x=5. By defining f(5) = 10, the discontinuity is removed. f(x) = x+5 for all x.

**Math - PreCalc (12th Grade)**

just start checking: 5^1 <= 4^1 + 3^1 5^2 <= 4^2 + 3^2 5^3 > 4^3 + 3^3

**Math - PreCalc (12th Grade)**

Looks good to me. When finding a limit, first try just plugging in the given value. As long as you don't wind up with 0/0 or something else undefined, the resulting value is the limit, as long as the function is not defined differently on the two sides.

**Math - PreCalc (12th Grade)**

well, plug in x=2 and see what you get.

**math**

assuming the water heater actually sits in the pan, it occupies part of the area of the pan. So, the volume of the unused portion of the pan is π(11^2-9^2)(2)

**Grammar**

correct. The only mistake here is the word "grammaratically"! Maybe a bit too much capitalization, but I'm not sure that qualifies as grammar.

**Math - PreCalc (12th Grade)**

as x->3 from the left, (x-3) < 0, so |x-3| = -(x-3). -(x-3)/(x-3) = -1

**Math - Hmmm**

No, C is out because 8 ≠ 3.5+3.5+3 D is out because 10 ≠ 1+4+3

**Math - PreCalc (12th Grade)**

ok. so we have x + y + z = 15000 x = y + z + 3000 3x + 2y + 2z = 30000 Nope. That wasn't it. So, if #1 costs 3000 more than either #2 or #3, we have x + y + z = 15000 x = y + 3000 x = z + 3000 3x + 2y + 2z = 30000 No joy there, either. So, what about the choices? A: 3*9 + ...

**Math - clarify**

When you say Investing in the first venture will cost $3,000 more than investing in both the second and the third venture. do you mean #1 is 3000 more than both #2 and #3 combined, or 3000 more than either #2 or #3?

**Math - PreCalc (12th Grade)**

a = 5 b = 3 a^2 = b^2 + c^2 so, c = 4

**math**

p - .15p = 8000

**MATH**

Thanks for fixing the typo. What is the difficulty? What answer do you get?

**Physical Science**

well, if you buy into the fact that red+green+blue = white then the complement of any secondary color is the unused primary color.

**MATH**

and only two wrists!

**MATH**

and the rest are not

**math (check)**

3.14 * 8^2 * 5.7 = 1145.47

**math**

-2,5*780^2 + 2825*780 - 115,812.5 Is there a typo in -2,5? Evidently you use a period for the decimal point later on.

**derivatives - oops**

d/dx sinx = cosx

**math**

http://www.wolframalpha.com/input/?i=4x^2+cosx

**math - back to speed**

Reiny is, of course, correct, but given the choice of answers, I went with the assumption that they were just looking for knowledge of the area of the circle. And besides, who said that the flower areas were of any particular shape? Nothing says that the plants around the edge...

**math***1questions*****

pi * 7^2 = 154

**Calculus Help**

log y = log (e^-x) + log cos^2(x) - log(x^2+x+1) log y = -x + 2log cos x - log(x^2+x+1) 1/y y' = -1 - 2tanx - (2x+1)/(x^2+x+1) y' = -(1 + 2tanx + (2x+1)/(x^2+x+1)) * (e^-x cos^2x)/(x^2+x+1) Now, you can massage that for a few more steps, to get something that pleases you

**math**

(20)5/6-5A+11 50/3-5+11 17/3-5A

**math**

so, what number do you have to add to 7 to get 10?

**math, please help!**

1987 is 7/10 of the way from 1980 to 1990 So, what is 7/10 of the way from 8558 to 13807 ?

**Trigonometry - incomplete**

no diagram. Better explain a bit more, the relative positions of A,B,C,D

**AP Calc**

was the answer I gave in the 1st related question below incorrect? If so, do you have any suggestions?

**Math**

14x = 9

**Linear Algebra**

ok 3g^-2 b^2 = 3b^2/g^2 negative exponents are in the denominator 3/g^-2 = 3g^2 So, 3/g^-2 h^3 = 3g^2 h^3 missing parentheses?

**math**

decrease = 60 60/310 = ?

**Algebra**

is 1^1 + 2^2 = (1+2)^2

**Math - eh?**

not familiar with the notation fX(x) and fY(y) partial derivatives?

**algebra**

well, (x+y)^2 - (x-y)^2 = 4xy So, (x-y)^2 = 280^2 - 4*19951

**math**

.005(400^2) - 45(400) + 12000

**Algebra**

w(3w-1) = 30 (3w-10)(w+3) = 0

**physics**

minimal, or nominal? Sine I = P/E, what's 100/120 ?

**Algebra I**

10x - 9y = 46 -10x + 15y = 30 6y = 96 y = 16 now get x from either equation

**Math**

v = Bh where B is the area of the base Since the base is a triangle, B = 1/2 * 4 * 5 Now, since h=8, you can easily see that v=80

**Geometry**

6x-8 + 7x+3 + 3x-7 = 180 x = 12 So, evaluate for each angle, then sort them.

**Math**

((n+21)(3)-9)/5 = 30 n = 32

**PRE-CALC**

Looks like C to me Note that C covers more than just this set.

**Physics**

No work = force * distance since distance=0, no work.

**Science**

how did the discovery of nutrons change the atomic model

**Science**

what type of bond is a metal cation likely to form?

**Trigonometry**

by law of cosines, c^2 = a^2 + b^2 - 2ab cosC Now, having a,b,c and C, use the law of since to get A,B. sinA/a = sinB/b = sinC/c

**solid mensuration**

so, what is it you want to know? Just FWIW, I doubt that the altitude as given is correct.

**chemistry**

2C4H10 + 13O2 -> 10H2O +8CO2

**trigonometry**

oops. Forgot all those hours θ = 2π*5 + 2π/3 = 10π + 2π/3 = 32π/3 For the minute hand, that's the same value as 2π/3 but, θ/12 is now 32π/36 = 8π/9 which affects its trig function values immensely.

**trigonometry**

let the plane of rotation of the minute hand be z=0. So, the location of the tip of the minute hand is (9cosθ,9sinθ,0) Similarly, the location of the tip of the hour hand is (6cos θ/12,6sin θ/12,2) at 5:40 am, θ = 2π/3, so θ/12 = π/18 So...

**math**

(24/40)(340)

**Math**

Hmmm. how about y = -50 + 0.2x You can supply the units.

**College math**

4y = 3+9

**math**

s^2 = r^2 + h^2 = (d/2)^2 + h^2 s^2 = 4^2+9^2 = 16+81 = 97 s = 9.8

**Math - eh?**

I know it's a pain to write clearly, but until you do, the help will be thin on the ground. Sorry, I just can't parse that into a meaningful description of a figure.

**physics**

Hmmm. The way I see it, kinetic energy is lost during her rise up the ramp. So, at the moment of takeoff, her KE is 1/2 mv^2 - 1/2 mgh = m(1/2 * 7.59^2 - 1/2 * 9.8 * 0.741) = 25.17m Now, that means that her speed is then 7.10 m/s The vertical component of that is 5.81 m/s, so ...

**intro to comp**

I see only one OS that can act as a server.

**math**

(4.3 * 1.5) x 10^(-8+9)

**Algebra - typo?**

Before I start figuring, is there a typo in hour 3? All the other hours they sold n/n+1 - 1/n peaches, but that 3/4 instead of 1/4 bothers me.

**Algebra**

Generally FOIL refers only to binomials. For general polynomial multiplication/division, visit calc101.com Over on the right there are links for long multiplication and long division. That should help you understand the details

**algebra**

6a^2 + 15b^5

**Physical Science 9**

what type of bond is a metal cation likely to form?

**AP Calc**

x=e^t and y=t^2-3 dx/dt = e^t dy/dt = 2t dy/dx = (dy/dt)/(dx/dt) = 2t/e^t d^y/dx^2 = d/dt (dy/dx) * dt/dx d/dt(dy/dx) = -2(t-1)/e^t dt/dx = 1/(dx/dt) = 1/e^t d^2y/dx^2 = -2(t-1)/e^2t e^2t is always positive, so y">0 when t<1 Hmmm. From above, y' = 2lnx/x y"...

**Physical Science 9**

how did chadwicks discovery of nutrons change the atomic model

**Physical Science 9**

In an ionoic bond how many valence electrons would an atom have?

**Math**

just work with two at a time, and add up the distances. Do you understand the distance formula?

**math**

always

**Math**

(1/4) / (1/8) = 1/4 * 8/1 = 8/4 = 2 Think of it. 1/8 is half as big as 1/4, so there are two of them in 1/4.

**math**

2/3(6+3x)-7x (4+2x)-7x 4-5x

**Business Algebra**

.045x + .06(20000-x) = 987.50

**math**

r = 169/24

**algebra**

y = 82 + 3/4 x

**algebra**

you mention no equation, but if it is a^8 - a^2b^6 = 0 then a^2(a^6-b^6) = 0 a^2(a^2-b^2)(a^4+a^2b^2+b^4) = 0 so, a=0 or a = ±b or a^2 = (-b^2 ± √(b^4 - 4a^4b^4))/2 = (-b^2 ± b^2√(1-4a^4))/2 = -b^2/2 (1 ± √(1-4a^4))

**Alegbra**

(4.3x1.5) x 10^(-8+9) now just collapse the products

**AP Calc - Damon is, of course, correct.**

Dang! I was figuring the size of the legs, not the altitude. As Emily Latella would say, "Never mind."

**AP Calc - Merge answers**

Damon is right about the quadrant. My integral used the whole ellipse as the solid's base, not just the 1st quadrant. So, adjust the values as needed. However, Damon's triangles are not evaluated with the base as hypotenuse. So, the altitude will be base/√2. It i...

**AP Calc**

when the cross-section has a base of 2y, its height is thus y√2 So, the volume is v = ∫[-a,a] 1/2 bh dx = ∫[0,a] (2y)(y√2) dx = 2√2b^3/a^3 ∫[0,a] (a^2 - x^2)^(3/2) dx now it's just straightforward integration and evaluation

**4th Grade Math**

2/3 3/4 3/5, 4/5 ... any ratio where the less than twice the numerator

**College Algebra**

twice the concentration means half the volume, since the same amount of salt remains. So, we lost half of 16 oz, or ?

**AP Calculus**

Not sure what the "circumscribed" condition means, since any rectangle can be circumscribed. Damon's rectangles contain the approximated sections of curve within them, whatever that means. However, since the other choice of boundaries yields 2(1+e^2+e^4), its abs...

**statistics**

I assume you want two answers,since "all are correct and at least one is wrong" is impossible. P(all correct) = 1/4^6 P(some wrong) = 1 - P(all correct)

**Physics**

Hmmm. What's 92% of 750?

**math**

P = R-C = 4x - (2x+20) = 2x-20 When P=0, x=10

**geometry**

newarea = originalarea * (1/7)(1/7)(1/1)

**Mensuratin**

Rats - mixed up the dimensions. Use (3.14) (.5)^2 (7)

**Mensuratin**

not sure what "1 line" is in volume. Anyway, when you figure out how many ml the bottle holds, divide it by the pen's volume, which is (3.14) (3.5)^2 (0.5) cm^3 (or ml)

**геометрия**

since 600º = 360º+240º, you have cos 240º + sin 240º since 240º = 180º + 60º, you have -cos 60º - sin 60º = -1/2 - √3/2 = -(1+√3)/2

**FIN/370**

4800(1+.09)^10 = 11363.35

**Trigg**

you know that sin^2 + cos^2 = 1, so (x/2)^2 + (y/4)^2 = 1 x^2/4 + y^2/16 = 1

**English**

#1 is the most common usage. It is presumed that you want the glass of water in order to drink it, but the context will make that clear. #3 is much less common, but could mean the same thing. It is likely that English is not the speaker's native language. In Portuguese, fo...

**Math**

Not quite, Fiona. When you finally got an answer, you ought to have done just a sanity check. The average speed was somewhere near 200 mph, and the flew for 7 hours, a distance of 57 mile is ludicrous. since time = distance/speed, and the total time was 7 hours, then we want t...

**Math 117**

if y = f(x), the new shifted function will be y-10 = f(x) now just solve for the new y

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