# 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

**hello jishka maths tutor please help me**

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

**Math (Check Answer)**

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