Friday
July 1, 2016

Posts by steve

Total # Posts: 41,536

math
well, how many tiles will it take? multiply that by the cost of each tile.
May 16, 2016

maths
start with the sum-to-product formula: sin(√(x+h))-sin(√x) = 2cos((√(x+h)+√x))/2)sin((√(x+h)-√x)/2) or, try substituting u = √x sin(√x) = √x sin(√x) / √x = u * sin(u)/u and you know that lim sin(u)/u = 1
May 16, 2016

Geometry
the distance between those two points is √125 The equation is (x+4)^2 + (y+3)^2 = 125 You have mangled the question somehow. None of the equations has the correct center or radius.
May 16, 2016

maths
Try that again so it makes sense.
May 16, 2016

Mech. Engr./Dynamics/Physics/Math
well, you can start with the observation that the horizontal velocity is constant at v0 * sinθ Now just figure the time needed for each hop, and see if the ball travels enough to skip a step or hit it twice. Of course, you will need to have data on the height and width of...
May 16, 2016

mathematics
if they are the sides of a hexagon, the just add them up.
May 16, 2016

Math
all correct
May 16, 2016

math
7.5" = 10' 10.5" = 14' 10x14 = 140 ft^2
May 16, 2016

Math
review your basic trig functions. Draw a diagram, and you can easily see that cosθ = 1.5/6
May 16, 2016

Pre-Calc College
the fraction left after t minutes is (1/2)^(t/29) so, after two hours (120 minutes), the fraction left is 1/2^(120/29) = 0.0568 To find how log it takes to get to 10mg, 650(1/2)^(t/29) = 10 (1/2)^(t/29) = 1/65 t/29 = log(1/65)/log(1/2) = 6.022 t = 174.65 or, almost 3 hours ...
May 16, 2016

Maths
100000cm = 1km so, the scale is 1cm : 1km that should help
May 16, 2016

math
the integers form an arithmetic sequence, with a = 1 d = 1 So, the sum of the 1st 1000 integers is 1000/2 (2+999) = 500500 This is just an illustration of what Gauss figured out as a kid. You can pair up the numbers starting from the ends 1+1000 2+999 3+998 ... 500+501 There ...
May 16, 2016

math
since they are equal, 2x = 100
May 16, 2016

Trigonometry
Draw a diagram, then take a look at the cot function and you will see that h cot21° - h cot32° = 75
May 16, 2016

math
If their digit's number means the sum of the digits, then there are lots of them. But if since a quotient is only defined for two numbers, that implies that the number is a 2-digit value. I can't think of any two digits whose quotient is 20 and whose sum is 11. I ...
May 16, 2016

Math
x = y-13 x = 3/4 y x=39 y=52
May 16, 2016

Math
4(n-1) = 12 n-1 = 3 ...
May 16, 2016

maths
If one part is 2/7 of the other, then we can divide 54 into 9 parts such that each is 6. Now we see that the two parts are 2*6 = 12 7*6 = 42 12 is 2/7 of 42
May 15, 2016

Integral calculus
As a check, the theorem of Pappus says that the volume is the area times the distance traveled by the centroid, which is 9π*6π = 54π^2.
May 15, 2016

algebra/trigonometry
the easy way is to remember that the sides of a 30-60-90 triangle are in the ratio 1:√3:2 You have a long side of 75, so the other two sides are 75/√3,75,150/√3 The string is the long side. Or, using trig, the length of the string, x, is found using 75/x = ...
May 15, 2016

Math
If we let x = weight of camera y = weight of lock z = weight of crown we have x+y=330 x+z=670 y+z=470 now just solve for x,y,z
May 15, 2016

Algebra
Usually the dependent variable is on the left side. Its valye depends on the expression on the right side. The equation tells how to calculate the result of assigning a value to x.
May 15, 2016

Math
Assuming they paid the tip on the price after discount, then each paid 97.38*0.65*1.18 -------------------- = $18.67        4
May 15, 2016

mathematics
9/9^2 = 15/x^2
May 15, 2016

Maths
m = kn/p^2 now you can find k.
May 15, 2016

Algebra
3 ∑ k^2 k = -1
May 15, 2016

Geometry
atsa right
May 15, 2016

Algebra
note that the numbers grow by 3's. So, the sequence is 3k+ something. 3*1=3, but the first term is 5, so the terms are 3k+2 The sum is thus 4 ∑ 3k+2 k=1
May 15, 2016

math NEED HELP
4^3 * 4^4 / 4^9 = 4^7/4^9 = 1/4^2 or, 4^(3+4-9)
May 15, 2016

Algebra
it is clearly C, because (7x-14) = 7(x-2) but you cannot have a denominator of zero. So, while the fraction is equal to 7 almost everywhere, the value of x=2 is excluded because then the fraction is 7(0)/0 and is undefined. The numerator can be zero whenever it wants, so x=7 ...
May 15, 2016

Algebra
well, A is true, but so is C. So, the answer is D. If you had solved the quadratic you would have found both solutions 7x+84 = -x^2+40x-6
May 15, 2016

Math
44lb * 1kg/2.2lb * 14day * 30mg/(kg-day) = 8400mg
May 15, 2016

maths
give google a try. First hit explores this topic http://mathforum.org/library/drmath/view/56394.html
May 15, 2016

math
1 and 2
May 15, 2016

Pre-Calc
Sure; it's just part of the expression. So, assuming we start with n=1, the powers and denominators go up as 3,5,7,9,... So, the sequence is -x^3/3!, x^5/5!, -x^6/7!, ... though I suspect that maybe we start at n=0. But you can fix it if that's the case.
May 15, 2016

Math
1/8 - 1/9 = 1/72 That's how much of the tank gets filled in one minute with both taps open, right? But the question is poorly worded...
May 15, 2016

Math
4x^2 + x + 9 = 0 the quadratic formula will provide you with the complex roots.
May 15, 2016

Math
use the pythagorean theorem.
May 15, 2016

Math
that is very bogus notation. Try rewriting it with ^ denoting a power, as x^2 = x squared And lose the combined fractions. Use parentheses to delineate the meaning. 2/3/4 might be (2/3)/4 or 2/(3/4) which are not the same.
May 15, 2016

Algebra
C is wrong. Check your +- signs during the expansion
May 15, 2016

Maths
smallest answer will come from subtracting the largest value from the smallest. So, 0 - 7654321
May 15, 2016

Prealgebra
no idea what two-ni means, but the product of 1 2/5 and b is 1 less than 2 1/2 of b can be written as (1 2/5)b = (2 1/2)b - 1 maybe you can take it from there...
May 15, 2016

calculus question ?
You are correct in both cases. Consider f(x) = 1/x and f(x) = tan(x)
May 14, 2016

math
since xy=k, a constant, you need y such that 4y = 8*24
May 14, 2016

Maths
surely you have the formulas necessary. Just plug in your numbers.
May 14, 2016

Geometry
looks good
May 14, 2016

Math
Huh??? The only one of those answers less than 4 hours is A!
May 14, 2016

Math help.
well, plug in -x+13 for y and you get -x+13 = x^2+6x+7 x^2+7x-6 = 0 This has two solutions, but they are not listed among the choices. Check for a typo.
May 14, 2016

Algebra
t^6 + t^3 - 8 = 0 now just use the quadratic formula for t^3: t^3 = (-1±√33)/2 Now you can use de Moivre's formula to get the various cube roots of those two values.
May 14, 2016

Physics
F = ma, so a = 4 m/s^2 v = at, so 8 = 4t. t=2 s s = 1/2 at^2 = 2*4 = 8 m
May 14, 2016

math
check for a typo. There are two solutions, but they are not listed.
May 14, 2016

Math
just do them step by step -x(5x-4) (-x)(5x) + (-x)(-4) ... 5k^2(-6k^2-2k+6) (5k^2)(-6k^2) + (5k^2)(-2k) + (5k^2)(6)
May 14, 2016

Algebra
to have one root, the discriminant must be zero. That is, 4+16m = 0
May 14, 2016

math (PLZ HELP ASAP)
p = 2d p+2 = 3(a+2) d = a+5 p+2 = 3(d-5+2) = 3(p/2 - 3) p+2 = 3/2 p - 9 p/2 = 11 p = 22
May 14, 2016

Math
same as the previous question. Just plug in the values and evaluate.
May 14, 2016

Math
just plug in their values: f(x)-g(x) = (3x+5) - (-x+9) now just simplify
May 14, 2016

Math calculation
how many oz per liter? multiply that by 2.5 divide that by 2.
May 14, 2016

math (pLZ HELP ASAP)
substitute t+7 for u and you get 10t + t+7 + 26 = 5(t + t+7) 11t + 33 = 10t + 35 t = 2 so, u=9 and the number is 29 check: 29+26 = 55 = 5(2+9)
May 14, 2016

math (pLZ HELP ASAP)
u = t+7 10t+u + 26 = 5(t+u) now just crank it out.
May 14, 2016

Maths
depends on the length of the wiper blade - inner and out radius. Then a = 1/2 r^2 θ
May 14, 2016

maths
greater than 96 odd with units less than tens. 97 121 71471928373 or many many others I think you have left out some information
May 14, 2016

ALGEBRA
well, 2+6 = 8, so ...
May 14, 2016

geometry
google is your friend. Try here: https://www.math.washington.edu/~king/coursedir/m444a00/syl/class/trapezoids/Trapezoids.html
May 14, 2016

Maths
.30a + .10o = .15(a+o) .15a = .05o 3a = o so as long as there are 3 times as many oranges as apples, this will work out. check: apples: 6 of 20 oranges: 6 of 60 total: 12 of 80 = 15% 30 of 100 30 of 300 60 of 400 = 15%
May 14, 2016

maths
the same (alternate interior angles)
May 14, 2016

Algebra Quadratic
you want the solution to mx-2 = x^2 to have a zero discriminant. So, since x^2 - mx + 2 = 0 has discriminant of m^2 - 8 I guess that tells you what m is, right? Take a look at http://www.wolframalpha.com/input/?i=plot+y%3Dx^2,+y%3D%E2%88%9A8+x-2,+y%3D-%E2%88%9A8+x-2
May 14, 2016

math
actually, its speed is the same. The velocity has opposite direction.
May 14, 2016

math
same as when it left. momentum is conserved.
May 14, 2016

Math
consider Mike and Fred as one person. At the table for 7, then there are 2*11P6 ways to seat them, since the 7th seat is always taken. and 5! ways to seat the others. If they do not sit at the big table, then there are 7! ways to seat that table and 2*4! ways to seat the other...
May 13, 2016

Algebra
(x+y)/2 > 0 x+y > 0 y > -x so, y can be positive or negative, depending on x. for example x = 3 y = -2 (x+y)/2 = 1/2
May 13, 2016

PLZ HELP ASAP math
p = 2d p+2 = 3(a+2) d = a+5 Now just crank it out.
May 13, 2016

Math
A The last digit must be 0 or 5, and the 1st digit is not 0, so ending in 0: 5*4*1 ending in 5: 4*4*1 B toss out all those starting with 8 or 9.
May 13, 2016

Geometry
the middle is the average of the two ends.
May 13, 2016

Geometry
you've posted a lot of these, and all you have to do is use your formulas. We can check your answers.
May 13, 2016

Geometry
clearly the base sides and the altitude will be 18, so v = 1/3 * 18^3
May 13, 2016

6th grade math
3/9 assuming that the pairs are together, so one draw get a pair. If the socks are loose and two draws are required, things are different.
May 13, 2016

Math
you can verify your work at http://www.wolframalpha.com/input/?i=%28%283x^4%29-%282%2Fy^5%29%29^9
May 13, 2016

Math
-n = 10
May 13, 2016

Math
Jen's answer was wrong in any case, but you should have used some parentheses to make things clear. All you need is a common denominator, as all the choices show. So, do what you do with normal numeric fractions: 6/(x+2) - 1/(x+9) = 6(x+9) - 1(x+2...
May 13, 2016

integration....
sorry - you cannot do ∫√(x dx) But, you can integrate √x dx since that is just x^(1/2) dx and the power rule gives you x^(3/2) -------------- = 2/3 x^(3/2) + C 3/2
May 13, 2016

Math
works for me.
May 13, 2016

Math
well, just start listing them: 7539 -> 1 78.. -> 4P2 79.. -> 4P2 8... -> 4P3 9... -> 4P3 now add 'em up.
May 13, 2016

math
well, a 12" tile covers 1 ft^2, right?
May 13, 2016

Math
just separate the variables: dy/(y+y^3) = dx then use partial fractions to integrate then plug in y(0) = 1 to find the constant.
May 13, 2016

Maths
depends on how far away the tree is.
May 13, 2016

Math
however, given the usual sloppiness online, I suspect we have 2/3 y + 4 = 12 2/3 y = 8 y = 3/2 * 8 y = 12
May 13, 2016

math
well, for any (x,y) the transformation is (x,y) -> (-x,y)
May 13, 2016

Math
"opposite" has no special meaning in math, but assuming you mean its additive inverse, that would be 13 + 1/9
May 12, 2016

Pre-Calc
the amount left in t years is 69*(1/2)^(t/12.4) so, plug in t=75 Note that that's about 6 half-lives.
May 12, 2016

Pre-Calc
you want t where e^.05t = 2
May 12, 2016

Math
maybe 9 10 38 40 40 85 lots of other vales could be used.
May 12, 2016

Geometry
clearly the height is 12, so the area is 1/2 * 6 * 12 = 36
May 12, 2016

Math, Algebra
No need to go to powers of 3, since 81 = 9^2. (9^2)^(3x+3) = 9^(2x-2) so, 6x+6 = 2x-2 x = -2
May 12, 2016

Math
x+y = 15 3y-4x = 4 now just crank it out.
May 12, 2016

Algebra
a road that is 48 meters wide? Man, that's some highway! And, after all the data, just what is the question? The volume of concrete needed?
May 12, 2016

calculus
just expand the polynomial and integrate f(x) = x^3+4x^2+3x
May 12, 2016

Differential Calculus
sorry about z. It is really found using the law of cosines z^2 = (8/5)^2 + 1^2 - 2(8/5)cosθ where θ is the angle between the hands. I'm sure you can figure that out.
May 12, 2016

Differential Calculus
with the center of the clock at (0,0), the distance z between the tips at t minutes after 12:00 is z^2 = m^2+h^2 z dz/dt = m dm/dt + h dh/dt m = 8/5 cos(π/30 t) h = cos(π/360 t) Now just plug in the numbers at t=120
May 12, 2016

Calculus
y = lnx The distance z from the origin is thus z^2 = x^2 + (lnx)^2 2z dz/dt = 2x dx/dt + 2lnx (1/x) dx/dt z dz/dt = (x+lnx/x) dx/dt at (1,e), z = √(1+e^2), so dz/dt = (1+1/1)(2)/√(1+e^2) = 4/√(1+e^2)
May 12, 2016

Math
20 the co- in cosine means sine of the complementary angle. If cos(90-A) = cos90cosA + sin90sinA = sinA
May 12, 2016

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