Monday
February 8, 2016

Posts by Steve

Total # Posts: 37,476

Calculus
draw a diagram. We have at a depth of h feet, a water surface with a diameter of h feet. So, h=2r v = 1/3 π r^2 h = 2π/3 r^3 dv/dt = 2πr^2 dr/dt so we have 9 = (2π)(4) dr/dt Now you have dr/dt, the rate that the water is rising.
December 14, 2015

Math
There are 16 possible rolls. So, how many of those total to 5?
December 14, 2015

Math
y can be anything. It is unrelated to x.
December 14, 2015

Math
well, if each pitcher holds 1/4 gallon, how many pitchers are there in a whole gallon? Then multiply that by the number of gallons...
December 14, 2015

MATH ASAP
Don't come rushing in here expecting someone to be waiting to give you an answer ASAP. We help when we see the problems. You do know that one yard is 3 feet, right? So, just multiply that by the number of yards. If you do it right, you will get 30 1/2.
December 14, 2015

Algebra
Don't know the choices, but one equation is .18(11) = .12(11+g)
December 14, 2015

Algebra
since distance=speed*time, (p-w)(2.5) = 400 (p+w)(2) = 400 Now just solve for w, the wind speed.
December 14, 2015

Math (help soon)
m/k = 12/7 k-32 = 5/7 k 4/7 k = 32 k = 56 m/56 = 12/7 m = 96 Now you can answer the questions
December 14, 2015

Math Order of operation
Just write the expression in the order you learn the facts: Adam has $450: 450 He spends $210: 450-210 he divides all the money into four parts and one part he keeps: (450-210)/4 Here you need the parentheses, because 450-210/4 means that only the 210 is divided into 4 parts. ...
December 14, 2015

Math
Did you actually draw the lines? The area enclosed is a trapezoid with height = 8 top base = 3 bottom base = 7 So now you can get the area
December 14, 2015

Geometry 12
Gotta tell me where F is. You do know that ABDE is a rectangle.
December 14, 2015

Geometry 12
If one base angle is 42, so is the other. And, the three angles total 180. The length of the sides does not matter.
December 14, 2015

math
2 of the 6 numbers are less than 3. So, is the die loaded?
December 14, 2015

Algebra
you know there is a fixed cost. So, start out with C(n) = 43.50 Now, that does not depend on n. What does? The number of pizzas. Each costs 4.50, so the total cost of the wages is 4.50n C(n) = 43.50 + 4.50n Easy as (pizza) pie, right?
December 14, 2015

MATH
add up the values. If there are n nickels, then they coins are worth 5n + 25(n+24) = 1110
December 14, 2015

math
cost c(x) = 3.21*m(x) revenue r(x) = x*m(x) profit p(x) = r(x)-c(x) Now go for it.
December 14, 2015

math
For A, the terms are a,ar,ar^2,ar^3,... For B=1/A, the terms are 1/a, 1/(ar), 1/(ar^2), ... = (1/a), (1/a)(1/r), (1/a)(1/r)^2, ... For sequence B, the 1st term is 1/a, and the common ratio is 1/r. So, it's also a G.P.
December 14, 2015

Math
I agree.
December 14, 2015

Science HELP PLZ
They all look correct to me, except I think #6 is B.
December 14, 2015

Algebra 2 (Math)
If you have no clue, then clearly you have not studied your material, since it must have been covered. If a parabola has vertex at (h,k), then the equation is y = a(x-h)^2+k You have y = -x^2+12x-4 = -(x^2-12x) -4 Now recall that (x+n)^2 = x^2+2nx+n^2 That means that you have ...
December 14, 2015

Algebra 1
clearly, f = 20+30h
December 14, 2015

Algebra
the still-air speed is the average of the other two speeds, since the same amount is added or subtracted to get the final air speeds.
December 14, 2015

Mathematics
so, did you try the rule? why not show what you got? If y = u/v, where u and v are functions of f, then y' = (u'v - uv')/v^2 In this case, that means y' = {(1)(cosx) - (4+x)(-sinx)]/(cosx)^2 At x=0, y = (4+0)/(1) = 4 y' = [(1)(1)-(4)(0)]/1^2 = 1 So, the ...
December 14, 2015

math
frequency: 2*8=16 area: 4*80=320
December 14, 2015

Mathematics
so, assuming that you want to find x where (2+x)(-sinx) = 0, then you must have either 2+x = 0 or -sinx = 0 I expect you can solve both of those. This shows why we always set the product of factors equal to zero. If a product is zero, then at least one of the factors must be ...
December 14, 2015

math
Here is a related question. A man left his house and walked 5 miles south, then 5 miles east, then 5 miles north, at which time he was back at his house, and a bear was trying to get in. What color was the bear?
December 14, 2015

multiplication
42
December 14, 2015

Math
well, for any A.P., the nth term, Tn is Tn = a + (n-1)d So, plug in your numbers.
December 14, 2015

Math
Recall that Sn = n/2 (2a+(n-1)d)
December 13, 2015

plane geometry
recall that the area of a segment is a = 1/2 r^2 (θ-sinθ) If the longest chord is c, then (c/2)/r = sin(θ/2) So, now we have 27.5 = r*sin(θ/2) 330 = 1/2 r^2 (θ-sinθ) Solve those two and you have θ = 1.24 so, r = 47.33 as always, check my math
December 13, 2015

Pre-Calc, please a.s.a.p!!
(a) as with all parabolas, max height at t = -b/2a = 304/32 (b) max height is d(304/32) (c) find the roots of d(t)=500. d(t)>500 between the roots. (d) hits ground at d(t) = 0. t=304/16 Don't forget what you know about parabolas from Algebra I.
December 13, 2015

Math
If they cost $n and $w per yard, then we have 14n+20w = 1738 16n+25w = 2102 Now just solve for n and w.
December 13, 2015

math
the cost for the parts must add up to the cost for the mix, so r+n = 40 4r+6n = 4.75*40
December 13, 2015

Math
f1(0) = 2 f2(0) = 2 So, f is continuous. If a tangent exists, the slope from the left must be the same as the slope from the right. f1'(x) = -2-2x f2'(x) = 2 f1'(0) = -2 So, there is no tangent. You can see this from the graphs below. They touch at (0,2), but the ...
December 13, 2015

maths
That would be 1*P(1red)+2*P(2red)+3*P(3red) Now just figure the probabilities of drawing 1,2 or 3 red balls.
December 13, 2015

Math
v = ds/dt = 32.2t
December 13, 2015

Math
just define f(-2) to be some value other than its limit. f(x) = 2x for x ≠ -2 f(-2) = 0 The limit exists from both sides, but f is not continuous there.
December 13, 2015

calculus
Does ^3square root mean cube root? I'll assume so. Roots are just fractional exponents, so y = 7x arcsin(2x)+(1+4x^2)^(1/3) recall that d/dx arcsin(u) = 1/√(1-u^2) du/dx, so Now, using the product rule, y' = 7 arcsin(2x) + 14x/√(1-4x^2) + (1/3)(1+4x^2)^(-2/...
December 13, 2015

Inequalities
-x/3 - 5 < 12
December 13, 2015

History
how long can the treasurer of the united states serve?
December 13, 2015

Math
so, did you use MATLAB?
December 13, 2015

Trigonometry
The height h of the tree is given by h/10 = tan 65° Now, having h, you can get the distance f of the firefighter: f/h = cot 50° Now, the distance d between the dog and the firefighter is d^2 = 10^2+f^2
December 13, 2015

Tilili
(A+B)x(A-B) = AxA + BxA - AxB - BxB = BxA - AxB = -2(AxB) But, AxB is a vector, not a scalar. You have a glitch in there somewhere.
December 13, 2015

Calculus
nope. Look up arc length for parametric curves. ds^2 = (dx/dt)^2 + (dy/dt)^2 The distance traveled is the arc length.
December 12, 2015

math
.04x = .03(10000-x)+246
December 12, 2015

Math Help!
if b=2a, then a^2 + (2a)^2 = 1 5a^2 = 1 a = 1/√5 similarly for a=2b
December 12, 2015

delta prep (physics)
conserve momentum .27*200 = 4.1v
December 12, 2015

Function plz help!!!
How about starting with the definition of the equation? ∇^2(u) = 0 ∂u/∂x = 1/(1+y^2/x^2) (-y/x^2) = x^2/(x^2+y^2) (-y/x^2) = -y/(x^2+y^2) ∂^u/∂x^2 = 2xy/(x^2+y^2)^2 Now do ∂u/∂y and then form the equation.
December 12, 2015

geometrie
one side is the horizontal line from (4,5) to (9,5). It is clearly 5 units long. So, the other parallel side is also 5 units long, starting at (5,1)...
December 12, 2015

statistics help please
͡° ͜ʖ ͡°
December 12, 2015

Algebra
all polynomials are defined for every real number. So, the domain is all reals. Since a sloping line extends forever in both directions, what's your best guess as to the range? Surely you can fill in the table. Just multiply x by 6, right?
December 12, 2015

Algebra
x-intercept is where y=0 y-intercept is where x=0 so, just plug in 0 for y or x and find the two intercepts. Then just connect them with a line. Done.
December 12, 2015

calculus
just divide each term by x^2 and use the normal power rule: ∫x^n dx = 1/(n+1) x^(n+1)
December 11, 2015

math
This can be easily confirmed by noting that the equation is an ellipse: (x-1)^2/16 + (y+2)^2/4 = 1 The major axis is on the line y = -2, so that's where the tangents are vertical.
December 11, 2015

Ap physics 1
If we set the center of mass at 0, then we have 3.12*10^5 * 2.46*10^8 = m*d where m is earth's mass and d is the distance to the center of the planet.
December 11, 2015

Physics grade 11-
72 km/hr = 20 m/s So, the deceleration is (20m/s)/(.1s) = 200m/s^2 Now the force F=ma, so ...
December 11, 2015

Calulus
The FTC says that the value is F(6)-F(1) where dF/dx = 4e^x-3 F(x) = 4e^x - 3x + c F(6) = 4e^6 - 18 + c F(1) = 4e^1 - 3 + c So, ∫[1,6]4e^x-3 dx = 4e^6-4e-15
December 11, 2015

Calulus
y = 2x^3-3x^2+9x+5 y' = 6x^2-6x+9 y" = 12x-6 Now, just apply the basic rules extrema at y'=0 and y"≠0 y increasing where y' > 0 y concave up where y" > 0 inflection points at y"=0 Note: There may not be any extrema, and so on. ...
December 11, 2015

Algebra 1
try using the two-point form of the line. Your two points are (2,-17) and (8,-47)
December 11, 2015

Algebra 1
pick the one best suited to the problem. You know that you have a rate 0\of .50 for every mile. So, if x is the number of miles, you know you will have something like y = .5x But you have a flat fee of 4.25, regardless of the miles, which is tacked on as soon as the meter ...
December 11, 2015

Calulus
base side x height y 2x^2+4xy = 300 ==> y = (300-2x^2)/(4x) v = x^2y = x^2(300-2x^2)/(4x) = 75x - x^3/2 dv/dx = 75 - 3x^2 dv/dx=0 at x=5 So, the shed is 5x5x12.5, with v=312.5 ft^3
December 11, 2015

Math
since distance = speed * time, if the current is c and her speed is s, 35(s-c) = 1.75 15(s+c) = 1.75 Now just solve for c.
December 11, 2015

Calculus
cube side = x, so the area a = 6x^2 da/dt = 12s dx/dt Now just plug in your numbers.
December 11, 2015

Pre Algebra
Judging by the choices, I guess the burn time is in hours. So, you want the height h = 3*24/15
December 11, 2015

Pre Algebra
I suspect a typo: 80 should be 90. If so, then clearly, the burn time is just 15 times the height. You don't say whether the time is in hours or minutes. I suspect minutes, but that will require quite a tall candle, if you figure out how many minutes there are in 3 days.
December 11, 2015

Math
nope. Just the definition of the sine: h/14 = sin 70° For the law of cosines, you need two sides and their included angle.
December 11, 2015

Math
original b = h+3 (1/2)(b+3)(h+3) = (1/2)(h+6)(h+3) = 14 Now just solve for h, and then get b.
December 11, 2015

hbi pact for adults
well 50 lbs is 50 times a much as 1 lb, so expect 50 times as many nails.
December 11, 2015

math
that would be 3000/200000 = 3/200 express that as a percent.
December 11, 2015

Math
Let's scale down the figure by a factor of 25, so it is similar to a triangle with sides 4,10,11 you can use Heron's formula. sqrt(12.5(12.5-4)(12.5-10)(12.5-11)) ≈ 20 or, you can note that 4^2 = 10^2+11^2-2*10*11*cos(x) cos(x) = (100+121-16)/220 = 41/44 the area...
December 11, 2015

Chakote school solapur
just use the formula: 1/R = 1/10 + 1/20 + 1/60 The voltage does not matter. The formula works because each resistor allows a current to pass, and the currents add up to the total. Since E=IR, I=E/R, and you have a total current of 12/10 + 12/20 + 12/60 That current is the ...
December 11, 2015

maths (trigonometry)
Notice how Damon cleverly descried a poorly constructed problem, and took a shortcut!
December 11, 2015

Math
Must be some special form. I tried an online integrator, and got (1/2)^(y+1) Γ(y+1)/y! But since Γ(y+1) = y!, that gives your answer. I'd suggest looking into integral forms involving the gamma function.
December 10, 2015

Algebra
you have the formula. Just plug in t=6 To find how long it takes to get to a million, 2105.22e^0.03t = 1000000 e^.03t = 475 .03t = ln 475 = 6.1633 t = 205.44 years Looks like 3% isn't gonna cut it, especially if you include inflation.
December 10, 2015

Math factoring
15x^2-35x+10 5(3x^2-7x+2) 5(3x-1)(x-2)
December 10, 2015

Math question word
x = desktop cost y = laptop cost x = y+350 .07x + .095y = 305 Now just solve for x and y
December 10, 2015

Finite Math
C(30,3) = 4060 any number means some subset of the power set of 30 elements. That is 2^30 = 1,073,741,824
December 10, 2015

Math
oh, ok total fruits: 12+4+8=24 so, now what do you think?
December 10, 2015

Math
'Twas brillig, and the slithey toves ...
December 10, 2015

compare and order fraction
or, if you use a common denominator -- in this case, 60. For example, 4/6 = 40/60 ...
December 10, 2015

MATH
Aside from the copy/paste of the inequality symbols, ok. Special symbols in various fonts get garbled at times. 22 <= 6x-2 <= 4x+16 24 <= 6x <= 4x+18 Now things start to get messy. You can't just subtract 4x from part of the setup; all or nothing. So, I'd ...
December 10, 2015

math
since 3/4 = 30/40, what do you think?
December 10, 2015

MATH
you can do both at once 3 < 5x-27 < 53 30 < 5x < 80 6 < x < 16
December 10, 2015

@Damon - Nice Catch
duh -- read twice, write once.
December 10, 2015

Algebra 2
Oops. That is just the integer lengths. I'm sure you can set down the two inequalities restricting x and y.
December 10, 2015

Algebra 2
7 <= x+y <= 22 So, just start listing x y 1 6..21 2 5..20 . . . 6 1..16
December 10, 2015

math
L=56+3D
December 10, 2015

math
3 months is 1/4 year, so discount by 2%
December 10, 2015

Maths
n(AuBuC)=12 n(AuB)=8, so n(C)=4 n(A'uB'nC)=n((AuB)'nC) That help?
December 10, 2015

Math
well, just plug and chug. f(x+h)-f(x) = 1/(x+h-1) - 1/(x-1) = ((x-1)-(x+h-1))/((x-1)(x+h-1)) = (x-1-x-h+1)/((x-1)(x+h-1)) = -h/((x-1)(x+h-1)) Now, divide that by h, and you have -1/((x-1)(x+h-1)) Now you can take the limit as h->0, and you end up with -1/(x-1)^2 at x=2, ...
December 10, 2015

Pre-calculus
This is just Algebra I. If there are a grams of A b grams of B .14a + .29b = 34.53 130a + 90b = 25430 Now just find a and b.
December 10, 2015

Algebra
they are the same, since multiplication is commutative.
December 10, 2015

maths
1/15th failed, so 14/15 passed
December 10, 2015

Algebra discount price
p-75 is ok But, a 55% discount means you only pay 45%, or p*.45 For C, just set them equal, as asked: p-75 = .45p .55p = 75 p = $136.36
December 10, 2015

algebra
OK. Y=28-6x. But, y>x, since it is the middle So, we have 28-6x > x 28 > 7x x < 4 So, we have several choices 3,10,18 2,16,13 1,22,8 ... But y is the middle, so only 3,10,18 works.
December 9, 2015

geometry
Note that the triangle described is a right triangle. The orthocenter is at the right angle, since the triangle can be inscribed in a circle, with the hypotenuse as the diameter.
December 9, 2015

similarfigures
it's called a proportion
December 9, 2015

analtyic geometry
so, add up the sides to make 260. That will give you x, and thus the dimensions of the yard.
December 9, 2015

Math cosine law
Did you draw your triangle? Did you review the law of cosines? x^2 = 185^2 + 325^2 - 2*185*325*cos18°
December 9, 2015

Math
the Greek letter is pi, NOT pie!! just use your addition formulas. sin(x-y) = sinx*cosy - cosx*siny Draw your triangles for x and y. sinx = √3/2 means cosx = 1/2 cosy = 12/13 means siny = 5/13 Now just plug in the numbers.
December 9, 2015

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