Saturday
April 19, 2014

Posts by STEVE


Total # Posts: 21,784

Math
the wall, ground, and ladder form a righ triangle, with the ladder as hypotenuse, so, x^2 + 4^2 = 12^2 supplementary angles add up to 180 degrees. So, x + 3x+2 = 180 one angle is x, the other is 3x+2. Solve for x, and you're almost there.

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...

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