# Posts by steve

Total # Posts: 51,710

math
oops. Forgot to edit my id...

Algebra
amplitude: (14-4)/2 = 5 center line: (14+4)/2 = 9 so, we can start with y = 9cos(kx) the period is 5+5 = 10 hours, so 2?/k = 10, making k=?/5 y = 9cos(?/5 x) The high tide was at 7:00, rather than midnight, so y = 9cos(?/5 (x-7)) or y = 9cos(?/5 x - 7?/5) see http://www....

Geometry
Interesting. I did it like this: 2x+2y = 50, so x+y=25 x+y+h = 40 25+h = 40 h = 15

Geometry
works for me. I hope you calculated BD and didn't just guess around till you got a number that worked.

math
.09x + .05(20000-x) = 1680

Geometry
the distance is ?(12^2+(15-10)^2) = 13 Maybe you should have shown your work.

geometry
drop an altitude from M to P on KN. Then PM = ?(15^2-9^2) = 12 the area is thus (9+18)/2 * 12

Science
what do you think?

math
4.250 anything less, say, 4.249 will round down to 2.2

math
4.30 I think

Math
each side of the triangle is the sum of two radii.

trig
h = 2+10sin58°

math
x y -2 9 -1 4 0 -1 1 -6 2 -11 Note that as x goes up by 1, y goes down by 5. So, start with y = -5x Now, y(0) = -1, so the rule is y = -5x-1

Algebra 2
take a look at the graphs, and it should be clear. Or, study your text and apply the rules. http://www.wolframalpha.com/input/?i=plot+y%3D1%2Fx,+y%3D1%2F(2x-4)

Algebra
(2?5+3?7)^2 (2?5)^2 + 2(2?5)(3?7) + (3?7)^2 4*5 + 2*2*3*?35 + 9*7 ...

chemistry
the theoretical yield is 2 moles of CO2 for each mole of C2H6 So, how many moles of C2H6 did you use? how many moles of CO2 in 5.76g? compare your yield with the possible yield.

Algebra/Trig
the height the ladder will reach is 12sin75°

Trig
h = 2+10sin58°

Math
the horizontal speed is constant, at 90cos60° ft/s, so just use that speed for 3 seconds to find the distance.

math
just like the previous ball team question. You're not going to put in any effort?

math
this is just like the last one. Just write an equation for each statement. To start with, r+w+b = 28 ...

math
If they lost x, then x + 3x+14 = 130

Maths
the volumes are A:?r^2(8h) = 8?r^2h B:?(4r)^2h = 16?r^2h

maths
x/y = 2/3 (x+8)/(y+8) = 3/4 3x = 2y 4x+32 = 3y+24 4x + 32 = 3(3x/2)+24 x/2 = 8 x = 16 y = 24 check: 16/24 = 2/3 (16+8)/(24+8) = 24/32 = 3/4

algebra
try using + or - or other ascii operators, rather than copy/paste. The font is mangled.

maths
2/3 x = 4 + 3/5 x x/15 = 4 x = 60 check: 40 = 4+36

Algebra 2 check
stretch: 3/x reflect: 3/(-x) = -3/x shift: -3/(x+2)

math
see related questions below

math
google your question, and you will find several solutions

Algebra 2 struggle
1/(2x-6) = 1/2 * 1/(x-3) so, shifted right 3 and vertically shrunk by 2. Hmmm. Not a choice. So, equivalently, 1/(2x-6) = 1/(2(x-3)) shifted by 3, horizontally shrunk by 2. (D) http://www.wolframalpha.com/input/?i=plot+y%3D1%2Fx,+y%3D1%2F(2x-6)

Math help
no, that would make it seem like y(0) = 3 But that is not an asymptote. You get a horizontal asymptote when y approaches some value for very large x. Try (C) http://www.wolframalpha.com/input/?i=plot+y%3D3+%2B+1%2Fx,+y%3D3-3%2F(x%5E2%2B1)

physics
Ooops. My bad. It should have been 55.5F = 250 F = 4.5N

physics
F = ma, so a = F/m s = 1/2 at^2 = 1/2 (F/m) t^2 so, 1/2 (F/0.9)*10^2 = 250 F = 55.5 N

maths
you want an 8 degree drop. Each degree takes 30 minutes, so ... and 6:00 is how many 30-minutes periods after 3:00?

math
if you draw the diagram, you can see that the sides of ABCD are the hypotenuses of triangles formed at the corners of EFGH. So, the sides of ABCD are 1/?2 as long as the sides of EFGH. So, the area of ABCD is 1/2 the area of EFGH: 24 cm^2

math
The outer radius R=2.25 cm The inner radius r=2.25-0.25 = 2.0cm So, the volume of pipe is 2.1 * ?(R^2-r^2) = 210cm * ?(2.25^2-2^2)cm^2 = 701 cm^3 Now you can get the mass of the pipe.

math
5cm = 0.05 m So, the volume is 0.05m * 1.8*10^4 m^2 = 9*10^2 = 900m^3 Check for typos ...

hello reiny damon steve can you help me physics
This should help. http://hyperphysics.phy-astr.gsu.edu/hbase/gpot.html

calculus
The loop is formed when x=0, or t=±?3 So, the area is ?[-?3,?3] y(t) dx/dt dt = ?[-?3,?3] (6t^2)(3t^2-3) dt = 144?3/5

calculus
for the horizontal tangent, you want dy/dx = 0 dy/dt = 3t^2-16 dx/dt = -2t dy/dx = (3t^2-16)/(-2t) dy/dx = 0 when t=±4/?3 That is, where x = 59/3 for the vertical tangent, you want dx/dy = 0, or t=0 The loop is formed where y=0. That is, t(16t^2-1) = 0 Or, t=0 or &...

Maths
If the height of the prism is h, then its area is 2s^2+4sh If the pyramid has slant height l, then its area is s^2 + 4sl So, we just need to solve for l in 2s^2+4sh = s^2+4sl s^2+4sh = 4sl Hmm. It appears that by "square prism" you mean "cube," since in ...

calculus
just crank it out: s = ?[6,7] ?(x'^2+y'^2) dt = ?[6,7] ?((2/3)^2+(4t/(t^2-9))^2) dt = ?[6,7] ?((2/3)^2+(4t/(t^2-9))^2) dt = ?[6,7] ?((t^2+9)^2/(9(t^2-9)^2)) dt = 2/3 ?[6,7] (t^2+9)/(t^2-9) dt = 2/3 ?[6,7] (t^2+9)/(t^2-9) dt = 2/3 ?[6,7] 1 + 3/(t-3) - 3/(t+3) dt = 2/3 (...

trigonometry
4sin(x)-5cos(x) = ?41 (4/?41 sinx - 5/?41 cosx) so, cosØ = 4/?41 sinØ = -5/?41 Ø = -0.896 Note that Ø is in QIV, since sinØ is negative

Maths
1. well his final position is (-2.255,-4.288)

Calculus
So, let the width of print be x, and the height be y. xy = 8 y = 8/x That means that the area of the page is a = (x+2)(y+4) = (x+2)(8/x+4) = 4x+16+16/x da/dx = 4-16/x^2 So, find where da/dx=0 for minimum area. Note that I used x and y for the dimensions of the printed part. It...

Algebra
Right triangle ABC has the right angle at C. Angle B is 18.5° and side a is 17.9 centimeters.Find the length of the hypotenuse.

Trig
just use the Pythagorean Theorem: ?(54^2-46^2) = ?800 = ?(400*2) = 20?2 = 28.3

Trig
yes. check that 8^2+15^2 = 17^2

calculus
you have two answers. One will be greater than 8, so it is useless. So, use (10-2?7)/3 = 1.57 max v = 64(10+7?7)/27

calculus
just plug and chug: s = ?[0,2?] ?(x'^2 + y'^2) d? Using symmetry, we can take just one arc, and s = 4?[0,?/2] ?((-54cos^2?sin?)^2 + (54sin^2?cos?)^2) d? this simplifies quite nicely

Math (Integrals) (Using given method)
yes. so you have 1/2 ?sin2x dx let u = 2x, du=2dx and you have 1/4 ?sinu du = -1/4 cosu = -1/4 cos(2x) + C

calculus
?[0,4] ?(1+y'^2) dx = ?[0,4] ?(1+(12x^2+3)^2) dx

math
two bases 10*3 two sides 12*10 two sides 12*6

math
you can play around here, and see how things work: http://www.wolframalpha.com/input/?i=plot+3%2F7+x+%2B+6,+3%2F7x-3

Calculus
3.18-? = 0.0384 0.0384/? = .0122 = 1.22%

Algebra
B+A

Science
see related questions below

trigonometry
using the quadratic formula, sin(x) = 3/4 (1±?5) = -2.4 or 0.927 Now just find the two values of x which make that work.

math
42

Math
area of triangle base: 0.5*3.1*3.5 = 5.4 cm^2 volume = 5.4*21 area = 3*21*3.5 + 2*5.4

This appears to involve Airy functions, which are not your usual elementary functions. See http://mathworld.wolfram.com/AiryFunctions.html

Physics
I suspect a typo. No way is a wire going to increase in length by a factor of 10. Also, your coefficient is lacking some units. In any case, if it grows by 16.66*10^-6 cm for each °C, just divide the length increase by that number.

math
Let's say the initial rate is 6% In that case, the value after 44 years will be [4000(1+.06/2)^(2*22)](1+.0628/4)^(4*22) = 57,843.92 If the initial rate is not 6%, just change it in the expression above and re-evaluate.

Calculus
well, just plug in x=4! (f(4)-5)/(4-2) = 1 f(4)-5 = 2 f(4) = 7 In the absence of anything to indicate that f(x) is not continuous, I assume that lim(x->4) f(x) = f(4)

maths steve plz steve reiny help am dieing
That's "dying" and I have no ideas what your three angles are supposed to be. If they are the angles of a triangle, just draw a line at one vertex, parallel to the opposite base. Next, recall that alternate interior angles between parallel lines are congruent. ...

Pre algebra
C = 6P

word problem
x+y = 12 2x+3y = 29

geometry
the slant height of the pyramid is the altitude of each triangular face. Now you have four triangles, and you know their base and height. I assume you can take it from here.

Math
compare 6/9 to tan35°

Math
4/x = 0.25

math
as written, it is linear. But it is an odd way to write it. If you meant 2•3n-1 it is exponential

Math
If you take all the numbers from 1 to 30, there are 15 multiples of 2 7 multiples of 2^2=4 3 multiples of 2^3=8 1 multiple of 2^4=16 So, 2 occurs 15+7+3+1 = 26 times N = 26

Not so. Just expand the expression 5+2(r+7) = 5+2r+14 = 2r+16 2+5(r+7) = 2+5r+35 = 5r+35 Try that with the other pairs, and see which comes out with both sides the same.

math
240/1.2c = 240/c - 4

Math
you are correct that there are 4 lights. But that means one at each end, and two in the middle. There are only three spaces between lights, of 2m each. It's always better to draw a diagram, and this would have been clear.

algebra
5/7 x = 15000 x = 21000

maths
there are only 5 even digits. So, if each us used at most twice, that makes a total of at most ten digits used. Looks like your sequence can consist of only two 5-digit numbers. One such pair is 22446 68800

Math
kinda vague, eh?

math
s = r? You have s and ? (hint: a full circle is 2?), so find r. a = 1/2 r^2 ? then let 'er rip and that's pi, not pie!

calculus
The region of interest is just a small patch above the x-axis. y ranges from 0 to 1, but the right boundary changes at 1/?2. The volume consists of a cylindrical ring of thickness 1/?2 plus a shape with curved edge. using shells of thickness dy v = ?2?rh dy where r=y+1 and h=x...

maths
If he started with x, then (x-4)/2 = 30

maths
m/j = 5/7 j = m+18 solve for m and j. Then you want (m+9)/(j-9)

calculus
exploiting symmetry, we can say a = 2?[0,?/2] 1/2 r^2 d? = ?[0,?/2] sin2? d? = 1

calculus
y = r sin? x = r cos? dy = sin? dr + r cos? d? dx = cos? dr - r sin? d? so, the slope of the tangent line is dy/dx = (sin? dr + r cos? d?)/(cos? dr - r sin? d?) at ?=?, dy/dx = r d?/dr = r(-6/r^2) = -?^2/6 so, now we have a point and a slope, so the tangent line is y = -?^2/6...

calculus
r^2(cos^2?-sin^2?) = 1 r^2 cos^2? - r^2 sin^2? = 1 x^2-y^2 = 1

calculus
?[0,1] 2?x ds = ?[0,1] 2?x?(x'^2 + y'^2) dt = ?[0,1] 2?t^3?((3t^2)^2 + (2t)^2) dt Not an easy one -- it will involve integration by parts. http://www.wolframalpha.com/input/?i=%E2%88%AB%5B0,1%5D+(2%CF%80t%5E3%E2%88%9A((3t%5E2)%5E2+%2B+(2t)%5E2))+dt

calculus
a = ?[0,2] ?t (2t-2) dt = 8?2/15

MATH
it depends on what you are given. If you draw a diagram of the situation, you will find that tan? or sin? will probably give you your answer.

Physical Science
What will be the total resistance and current in a parallel circuit with a 15-volt battery and 3 10-ohm resistors?

Math
OK you started with 90 equations You didn't attempt 2 so 90-2=88 You missed 14 so 88-14=74and -14 for wrong answers You got 74 correct so 74*4= 296 and then 296-14=282 total score

algebra
-7?(6-5)?(54) = -7(?1)(3?6) = -21?6 I suspect a typo...

Calculus
Consider g(x) = f(x)-x g(0) = f(0)-0 >= 0 g(1) = f(1)-1 <= 0 since g is continuous, either g(1)=0 or g(1) < 0. If g(1) < 0, the Intermediate Value Theorem tells us that at some point c in the interval, g(x) = 0

math
it would be e^(sin x^2)*2x - e^(cosx) * (-sinx) This is just the chain rule via the back door. If F(t) = ?f(t) dt then ?[u,v] f(t) dt = F(v) - F(u) Now take the derivative, remembering the chain rule.

Calculus
#1. No consider f(x) = e^(-x^2) #2. No consider f(x) = -x^2 See what you can do with #3.

Algebra 2 check my last answer?!
where did you learn to write fractions? 2?/3 is the way to write it. However, your choice is not quite correct. You forgot the reflection part. So, the correct answer is f(x) = ?10cos(2?/3 x)+10 -10cos(2?/3 x) has max/min at 10,-10 and is a reflection of cos(2?/3 x) Now add 10...

pre-calc
S1: 2 | 1^2 + 7*1 2 | 1+7 2 | 8 true do likewise for n=2,3

algebra
I shall use x instead of whatever character you chose to copy/paste. The graph of y = a sin bx has amplitude = |a| period = 2?/b so, what do you get?

Trigonometric Functions?
quite a few maybe the easiest to use is wolframalpha.com desmos.com fooplot.com https://rechneronline.de/function-graphs/ are all good sites with lots of versatility

statistics
for any general question, google is always a good place to start. https://www.google.com/search?q=estimated+probability&ie=utf-8&oe=utf-8

Math
15/x = 3/4 If the areas are in the ratio 9:16 then the sides (which are the square root of the areas) are in the ratio ?9:?16 3:4 = 15:20

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