Monday

February 8, 2016
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*