Saturday
September 5, 2015

Posts by steve


Total # Posts: 33,322

Algebra
well, geez. Plug in t=8 and do the, uh, math!
July 11, 2015

math
just a little nudge can usually help.
July 11, 2015

math
x = y-8 2y = 4x Now do a little substitution for y, and you can easily find x.
July 11, 2015

math circle geometrics
draw a radius perpendicular to the chord. If the center of the circle is O, the chord is AB, and the midpoint of the chord is P, then you have a right triangle where the leg OP is 5, and the hypotenuse (the radius) is 7. So, PA=PB is half the chord length.
July 11, 2015

math probability
answered in a related question below.
July 11, 2015

physics
the x-velocity is 43.4/1.8 = 24.111 m/s so, the ball is hit at an angle θ such that cosθ = 24.111/26, so θ = 21.97° So, the y-velocity is 26sin21.97° = 9.73 m/s. The height of the ball is y = 9.73t - 4.9t^2 So, when caught after 1.8 seconds, y(1.8) = 1.638
July 11, 2015

MTH 156
you know the perimeter is 2(length+width) So, f(1,8) = 2(1+8) = 2(9) = 18 and so on for the others. To produce an output of 16, all you need is two numbers that add up to 8.
July 10, 2015

Math
since (x^a)^b = x^(ab) (√3)^2 = 3 So, if √3 = 3^a, (3^a)^2 = 3^(2a) = 3^1 So, 2a=1 √3 = 3^(1/2) The nth root of x is x^(1/n)
July 10, 2015

Maths
Oops. The 4th term is C(6,3)
July 10, 2015

Maths
The (x^3)(1/x)^3 term will be constant. That is the 4th term of the expansion. So, what is C(6,4)?
July 10, 2015

Math
r = 2j+3 r-3 = 4(j-3) 2j+3-3=4j-12 j=6 in 10 years, Joe will be 16
July 10, 2015

maths,integration
v = 4-t s = 4t - 1/2 t^2 + c s(0) = 5, so c=5, and s(t) = 4t - 1/2 t^2 + 5
July 10, 2015

Algebra
with interest rate r, continuous compounding for t years results in a growth factor of e^rt. So, you want e^5r = 4 r = ln4/5 = .277, or 27.7% Which formula were you using to get 11% ?
July 10, 2015

Maths
answered in related questions below.
July 10, 2015

math
you have two pairs of equal sides. So, the two sides you have are half the perimeter.
July 10, 2015

precal
There are lots of good Riemann Sum online calculators. This one is easy, though. The interval widths are 0.5, so all you have to do is evaluate 0.5(f(.5)+f(1.0)+...+f(3.0))
July 9, 2015

math
d$ = 100d¢ You want to convert dollars to whistles: 100d¢ * (w whistles)/c¢ = 100dw/c whistles The easiest way to do this kind of thing is to treat it as a conversion from one unit to another. You can always multiply by 1 without changing anything. Since w ...
July 9, 2015

math
The common denominator of all those fractions is 120. So, say there are 120 members Then 45 are R, 75 are D Also, 80 are men, so 48 are Dm. That leaves 75-48=23 Dw So, 23/120 are Dw
July 9, 2015

math
.08c = .12d 2c = 3d so, c+d = 3/2 d+d = 5/2 d or c + 2/3 c = 5/3 c Not sure what your choices are...
July 9, 2015

Calculus Partial Derivatives
ignoring all the stuff with F and f, I assume you meant y = f(x+at) + f(x-at) ∂y/∂t= f'(w)∂w/dt + f'(v)∂v/dt = a(f'(w)-f'(v)) ∂2y/∂t2 = a(f"(w)∂w/∂t - f"(v)∂v/∂t) = a^2(f"(w)+f"(v))
July 9, 2015

chemistry
14.8/.917 g
July 9, 2015

Math
1 and 2 3 is false, since √2.25 = 1.5 is a radical that is not a whole number, but is not irrational
July 9, 2015

Math
whole natural excludes zero integers include negatives rational includes integers and fractions
July 9, 2015

Algebra
By the way, 2x^3 sqrt(10/x) is also correct. So, good work, I think.
July 9, 2015

Algebra
If you'll allow one more step, 2x^2 sqrt(10x)
July 9, 2015

math
If the committee is really 3 men, then Mary can't be on it at all. I suspect you meant 3 people. In that case, if either John or Mary is on the committee, then there are only 13 other people to pick for the other two seats. That gives us Committees with John: 13P2 = 156 ...
July 9, 2015

math
100-999
July 9, 2015

Mathematics
So, did you actually check your answer? tx=180 means ty=144 So, total time for X is 180+80=260 total time for Y is 144+80 = 224 distance from A of X to meeting place is L/260*80 distance from B of Y to meeting place is L/224*80 Add those up and you do not get L. Your mistake ...
July 9, 2015

Physics
work = force * distance, so assuming European conventions, where the ground floor is floor zero, work = 60*9.8*10 * 3*12 Joules power = work/time, so p = work/12 Watts
July 9, 2015

Math
70+W <= 150
July 9, 2015

Algebra
Since time=distance/speed, if his speed is s and the current's is c, then 15/(s+c) = 15/(s-c)-5 15/(2s+c) = 15/(2s-c)-1 Now just solve for s and c.
July 9, 2015

mathematics
I think you mean she sold 16 boxes, since she only had three different types. t+h+c = 16 40t+50h+60c = 800 That's not enough to completely specify a solution, but it will get you to t = c h = 2(8-c) So, clearly c<=8. If we start listing the possibilities, we get c,t h 8...
July 9, 2015

math
a) the shortest sides are in the ratio 8/3 b) so are the perimeters.
July 9, 2015

math
just multiply 13 by 21/15, the scaling ratio.
July 9, 2015

Physics
since a = 2.7 m/s^2, at t=4.2, v=11.34m/s Then its acceleration drops to (13.0-11.34)/5 = 0.332 m/s^2 So, starting at t=4.2, x = -108 + 0.332t + 0.166 t^2 At 5.7s after the first phase, then x = -100.7
July 9, 2015

math
what should be added to 4 to get 6? 6-4, or 2. Same here. you need to add (-2/15) - (2/3 + 3/5) So, use the common denominator of 15 to work with the fractions.
July 8, 2015

math
The common denominator is 63, so you have 54/63 - 126/63 - 49/63 + 57/63 ...
July 8, 2015

maths
Not much to this one. 1/10 = 7/70 ...
July 8, 2015

maths
I'll assume you meant 1/(x+1)+1/(x+2)= 2/(x+10) Putting all over a common denominator, the numerator becomes (x+2)(x+10) + (x+1)(x+10) = 2(x+1)(x+2) 2x^2+23x+30 = 2x^2+6x+4 I expect you can take it from there, eh? Just beware spurious roots that might make any of the ...
July 8, 2015

Physics
the only equation you really need is d=vt, or t=d/v. That gives you 114t = 79t+36 35t=36 t = 36/35 That's how long it takes B to overtake A. In that time, A travels 79*36/35 = 81.26 km You can think of this another way by noting that B is traveling 35 km/hr faster than A. ...
July 8, 2015

algebra 1
-72-4x^2+8x^3-36x Geez, have you never noticed that polynomials are generally written in descending powers? Much preferred would be 8x^3-4x^2-36x-72 Using synthetic division, this is easy, or you can visit calc101.com, click on the long division button and then enter your ...
July 8, 2015

math (algebra)
If x passed, then the rest (36-x) failed. So, adding up all the grades, we have 78x + 60(36-x) = 71*36 This is just a mixture problem in other guise.
July 8, 2015

Math
6720/56 = 120 So, you have nPr = nCr * 5! That means that r=5. Review the definitions of nPr and nCr to see why this is so.
July 8, 2015

Calculus
I first thought of x^2+1, but f(-1) = 2. So, next, 2x^2+1 f(x) = x^2+1 for x in (-5,-1)U(-1,1) 3 for x = -1 2 for x > 1 I think this fits the bill.
July 8, 2015

math (algebra)
or, note that x^32-1 = (x^16+1)(x^16-1) = (x^16+1)(x^8+1)(x^8-1) ... and if you keep expanding the differences of squares, you wind up with (x-1) at the end.
July 8, 2015

Calculus
for the 2nd part, if a function is differentiable, it is continuous. Hence it has a limit at every point.
July 8, 2015

math
clearly on the nth day you win 5^n dollars. So, what's 5^11? Send me my 10% commission check, ok?
July 8, 2015

algebra
it takes t seconds to fall 125 ft, where -16t^2 = -15 Now, the velocity is just -32t. or, in one operation, -32√(15/16)
July 8, 2015

Computer Programming
odd - you know how to do multiplication. Do a division in the same way. Just copy the multiply routine, and replace * with /. Be sure to watch out for division by zero.
July 8, 2015

Computer Programming
looks pretty good so far. But your best help is your IDE, or the javac error messages. If there are no compile errors, then just run your code and see what it produces. It looks like you are getting a handle on things. Just keep poking around to find code snippets that do what...
July 8, 2015

algebra 2
you want the total area, less the pool, to be 105. So, that means that the border has width x, where (6+2x)(10+2x)-(6)(10) = 105 x = 5/2 ft or 2'6"
July 8, 2015

algebra
There are 7 octaves, plus an extra A,B,C A) Since there are 8 A keys, there are 8C5=56 ways to pick them. For the G keys, there are only 7C5 = 21 choices. For any key, consider it like this. Pick a key from the 1st octave. Now there are fewer octaves to pick the other 4 keys. ...
July 8, 2015

science
recall F=ma? m = F/a now just divide.
July 8, 2015

Maths
Good work, but you had to use a different function. Poorly set problem...
July 8, 2015

Calculus
If you got a single value for an interval, it doesn't look good for the kid. y = 4x-6arctan(x) y' = 4 - 6/(x^2+1) = (4x^2-1)/(x^2+1) y" = 12x/(1+x^2)^2 You are correct with what you got. But, what do you have when y" = 0? An inflection point. That's where...
July 7, 2015

Maths
(1+x)^(1/5) = 1^(1/5) + (1/5)/1! x + (1/5)(-4/5)/2! x^2 + (1/5)(-4/5)(-9/5)/3! x^3 = 1 + x/5 - 2x^2/25 + 6x^3/125 Using the series, we have a problem. It only converges when |x| < 1. I think what you really want to do is find (x-1)^(1/5), using x=32. Then you have x^(1/5...
July 7, 2015

Maths
if x ml of 100% alcohol are added, then you want .15(400) + 1.00x = .32(400+x)
July 7, 2015

Triginometry
Metro: 45tan56° Gammapro: 45(tan56°+tan24°) It always helps in these problems to draw a diagram. Then you can see which sides of the triangle you have, and so which trig functions to use. Of course, it also helps to review your trig functions, and study the similar...
July 7, 2015

Math
again, use tan. he adjacent leg in each case is 7.4 be sure to add 1.8 to the answers, since that's how high the observation point is.
July 7, 2015

Math
the height is just 25(tan33°+tan55°)
July 7, 2015

math
1st, plot the point (1,-3) Now, a slope of -1 means that every time x changes by +1, y changes by -1. Starting at the point (1,-3), move right 1 and down 1 to (2,-4) and plot that point. Then draw a line through the two points. And review the concept of slope...
July 7, 2015

Chemistry
well, clearly, each mole of Mg produces one mole of MgO.
July 7, 2015

math
s = j-4 j+5 = 2s Now go for it.
July 7, 2015

algebra
If Wendy's speed is w, their combined speed of approach is 2w+4 Since time = distance/speed, and they meet after 4 hours, 120/(2w+4) = 4
July 7, 2015

Math (Finite)
A: y = .60 + .02x B: y = .045x I guess you can take it from there, eh?
July 7, 2015

Algebra (Normal Distribution)
8 is 2 std below the mean 16 is 4 std above the mean P(Z>4) = .9772 P(Z>8) = .0227 P(4<Z<8) = .9772-.0228 = .9545 You can play around with this stuff at http://davidmlane.com/hyperstat/z_table.html
July 7, 2015

Maths
bounce height 1: 80 * 3/4 = 80(3/4)^1 2: 80 * 3/4 * 3/4 = 80(3/4)^2 ...
July 7, 2015

Algebra/ Pre Calc - eh?
is there a question somewhere in there? You can start off by noting that √(78.5/π) ≈ 5
July 7, 2015

Algebra/Pre Calc
If you park n cars for t hours, car 1: x = 3 + 2(t-1) others: 3/4 that amount, or 3/4 (n-1)*x So, the total amount will be f(n,t) = (3+2(t-1))(1 + (3/4)(n-1)) = (3n+1)(2t+1)/4 So, 3 cars for t hours is f(3,t) = 5/2 (2t+1) So, let's check, say, f(3,4)=45/2=$22.50 1st car: 3...
July 7, 2015

Math
Fill in the tens place, and then start reading what they tell you. xxx7x xx37x 9x37x 9437x 94379
July 7, 2015

Ucc
12,48,82,19,66
July 7, 2015

Not much of an Equation
Hmmm.
July 7, 2015

math
5 digit greater 60000 6xxxx My ones digit is less than my 10000 digit 6xxx{0,1,2,3,4,5} on my other digit are the same This is where I get lost.
July 7, 2015

phakamani secondary school
talk to your school counselor.
July 7, 2015

Math Statistics
virtually zero. since there is no replacement between draws, 1st # 1/58 2nd # 1/57 ... and so on multiply them all together
July 7, 2015

Grammar
1 is 2 is 3 are 4 were 5 have become If these trouble you, you need to review the forms of the verb "to be"
July 7, 2015

math
well, 515% is not 3/10 515% = 5.15 = 5 15/100 = 5 3/20 or 103/20 Not sure what you want to do with the 3/10. If your typo meant +, then just note that 3/10 = 6/20.
July 6, 2015

math
375/200 = (15*25)/(8*25) = 15/8
July 6, 2015

Math (Finite)
multiply the 2nd row of A by the 2nd column of B: (2)(-2)+(3)(6) = 14 Verify at http://www.wolframalpha.com/input/?i={{1%2C4}%2C{2%2C3}}*{{3%2C-2}%2C{4%2C6}}
July 6, 2015

physics 20
The first question makes little sense, but the second can be answered by solving 13s = 7.25s+350 s = 60.87 Since Jack has to stop after only 60 seconds, he'll watch Zeke's heels as he escapes. One more second and he'd have had zebra for lunch.
July 6, 2015

Calculus
assume all logs are base 3. We have log x^2 = 2log4 - 4log5 log x^2 = log16 - log625 x^2 = 16/625 x = ±4/25 Yes, the -4/25 is a solution, since only x^2 appears, so it's always positive.
July 6, 2015

Physics
speed: y' = 3.12t+1.04 acceleration: y" = 3.12
July 6, 2015

Physics
75000km * 1000m/km * 1rev/.300*2π m = 3.98x10^7 rev
July 6, 2015

Calculus
v = ft/s dv/dt is thus ft/s^2 (acceleration) Since gravity is constant, v' is constant.
July 6, 2015

Physics
(a) 65.0 m/s * 1rev/.700π m = 29.557 rev/s
July 6, 2015

math - eh?
Does the pi1: mean something? That's my question. Do you have one?
July 6, 2015

physics
A. So, how far does sound travel in 6.16 seconds? That is the round trip, so the berg is half that far away. B. same problem in reverse. How long to make a round trip of 2*2.21 meters? distance = speed * time time = distance/speed
July 6, 2015

F.g.c jos
the faces of the cube are 28^2 So is the base of the pyramid. So, the composite volume is 28^3 + 1/3 * 28^2 * 16
July 6, 2015

pre calculus
we know that the fraction remaining after t years is f(t)=e^-(kt) for some k. So, find k: f(227) = e^(-227k) = 0.68 k = 0.001699 So, f(t) = e^(-.001699t) I expect you can take it from here, ok?
July 6, 2015

Maths
google is your friend. I searched for your question and found a solution at http://openstudy.com/updates/53803effe4b04df7f2086291 There are surely others, maybe not quite so complicated.
July 6, 2015

math
at the surface of the earth, g=9.8, so his weight would be 60*9.8 = 588 Newtons
July 6, 2015

Physics
I think you need to specify more. F=ma, but we don't know how long it took to reach its ballistic speed, so we have no idea of the initial acceleration.
July 6, 2015

Science
man, never heard of google, or online dictionaries?
July 6, 2015

Science
neither. Galileo figured that out.
July 6, 2015

Math
Or, you can work it from the other side, which I find easier at the start: x + 2x-40 = 150 3x = 190 x = 63.33 2x-40 = 126.67-40 = 86.67
July 6, 2015

Science
first, that's stationary, since the rock is presumably not made of paper. How long does it take the glass to fall 1.5 meters? Then figure the horizontal speed using speed = distance/time.
July 6, 2015

physics
of course, the air does not have constant density, but under the given assumptions, you want to convert pressure to meters: 1 pa = 1N/m^2 1.04*10^5 N/m^2 * 1m^3/1.3kg * 1kg/9.8N = 8163m or 8.163km The folks who have climbed Mt. Everest (7855m) would be interested to know this...
July 6, 2015

Math
Just review the derivation of arc length in 3 dimensions, as at http://tutorial.math.lamar.edu/Classes/CalcIII/VectorArcLength.aspx s = ∫√(f'^2 + g'^2 + h'^2) dt So, for your problem, f' = √2 g' = e^t h' = -e^-t s = ∫[0,1]√...
July 6, 2015

Sequence
Clearly the sequence is not a geometric progression. It is just a sequence of squares. I think that should get you going.
July 6, 2015

math - eh?
There is no way to tell. The combined ages of the children in no way tells you how many children there are. It does provide an upper limit though, assuming each child is at least 1 year old. Not only that, but the system of equations using the given conditions has no solution...
July 6, 2015

  1. Pages:
  2. <<Prev
  3. 4
  4. 5
  5. 6
  6. 7
  7. 8
  8. 9
  9. 10
  10. 11
  11. 12
  12. 13
  13. 14
  14. 15
  15. 16
  16. 17
  17. 18
  18. Next>>

Members