Wednesday

November 25, 2015
Total # Posts: 35,772

**algebra**

since the height/shadow ratio is the same 5/3.5 = h/14 or, just note that the pole's shadow id 4 times as long, so the pole is 4 times as tall.
*November 1, 2015*

**Calculus 1**

looks correct. The fence is divided equally among lengths and widths.
*November 1, 2015*

**math**

if the dimensions of the pool are w and 2w, then (w+8)(2w+8) - w(2w) = 136
*November 1, 2015*

**Algorithm**

assuming you have filled in an array (call it days) of 12 elements, each with the number of days in the month, get date (m/d/y) split into month,day,year if day < days[month] then &nbrsp;&nbrsp;day++ else if month < 12 then &nbrsp;&nbrsp;day=1 &nbrsp;&nbrsp;month++ else...
*November 1, 2015*

**Math**

46.9825 - 0.85870x
*November 1, 2015*

**rew**

well, you know that v^2 = 2as so plug in your values for a and s.
*November 1, 2015*

**Abiboss**

it is easy to construct an equilateral triangle, giving you a 60° angle. Now you can double that and halve that for the two angles you want. That should get you started.
*November 1, 2015*

**MATH**

If I read your notation right, you have -3x/√3 54x^4 + 2/√3 16x^7 Seems kind of odd, so maybe it's wrong. But whatever, is there a question in here somewhere? Ahh. Maybe you have -3x∛(54x^4) + 2∛(16x^7) note that ∛27x^3 = 3x ∛8x^6 = 2x^2...
*November 1, 2015*

**Algorithm**

why not PROMPT “Please enter n” GET n m=0 WHILE m < n COMPUTE m = m+1 DISPLAY m ENDWHILE
*November 1, 2015*

**Calculus**

Why do you integrate over [-2,2]? The curves intersect at (-2,4) and (2,4) but what does the line x = 1/2 have to do with it? There's a region left of the line, and a region right of the line. Since we are rotating about the y-axis, I think we want the region from x=1/2 to...
*October 31, 2015*

**Calculus**

well, you have the function. The average rate of change is just (change in volume)/(change in radius). So, (i) (V(6)-V(3))/(6-3) (ii) (V(4)-V(3))/(4-3)
*October 31, 2015*

**Algebra**

You just have to find x such that f(x) = 12 2(x+8) = 12 x+8 = 6 x = -2
*October 31, 2015*

**ap physics**

C the horizontal motion does not affect the vertical speed. This is assuming, of course, that the 2nd ball was dropped from a height of 50m. The problem does not say.
*October 31, 2015*

**science**

how do you define the best view?
*October 31, 2015*

**math,fraction**

x*16 + 2 = 10 Now just find x.
*October 31, 2015*

**physics**

clearly the minimum deceleration time is (10m/s) / (5m/s^2) = 2 seconds the distance traveled is thus s(t) = 0.5*10 + 10*2 - 2.5*2^2 = 15m
*October 31, 2015*

**math**

Assuming a 24-hour clock and chime, that would be 24/2 (2+23) If it starts over again with one chime at 1:00, then the sum is 2*12/2(2+11)
*October 31, 2015*

**physics**

well, you know that m1 * d1 = m2 * d2 but don't forget the mass of the seesaw on each side of the fulcrum. You don't say whether or not the fulcrum is in the center, but it usually is for a seesaw. The only remaining question is: what the heck is a season?
*October 31, 2015*

**MATHS**

did you plot the points? Clearly the other two points are C:(4,0) and D:(1,4) So, the trapezium has bases 2 and 8, and height 4. Think you can take it from there?
*October 31, 2015*

**math**

(-0.25x - 3) - (1.5x + 1.4) -0.25x - 3 - 1.5x - 1.4 -1.75x - 4.4
*October 31, 2015*

**Physics**

what is the difference between separation and boundary?
*October 30, 2015*

**Math**

well, either sin4x=0 or cosx=0 so, 4x = 0,pi,2pi,3pi,4pi,... meaning x = n*pi/4 for n=0 to 7 or, x = pi/2 or 3pi/2 but those are already covered by sin4x=0 see http://www.wolframalpha.com/input/?i=+2sin4x+cosx
*October 30, 2015*

**G.G.S.S.**

20 m/s^2 * 1km/1000m * 3600s/hr = 72 km/hr/s So, it will take (72-18)km/hr ---------------------- = 3/4 s 72 km/hr/s or, you can convert km/hr to m/s and do it that way. Still, 3/4 second seems awfully fast braking for a train. Better check my math
*October 30, 2015*

**Maths**

well, try factoring it y = (x-1)((x-1)^2 - 4) = (x-1)(x-1+2)(x-1-2) = (x-1)(x+1)(x-3) That help? Naturally, the y-intercept (at x=0) is at y=3
*October 30, 2015*

**Math**

well, for x <= 25, f(x) = 8.80 + 0.6686x Now what about for x > 25?
*October 30, 2015*

**Math**

Looks good to me.
*October 30, 2015*

**math**

type in your functions here and see all the details. http://calc101.com/webMathematica/long-divide.jsp
*October 30, 2015*

**English**

thank you
*October 30, 2015*

**English**

What is the noun clause in the following sentence? I heard that the book is set to release soon.
*October 30, 2015*

**suncrest high school**

reflection in the x-axis takes (x,y) -> (x,-y) so, just change the signs of all the y-values.
*October 30, 2015*

**Maths**

f(x) maps vales in the domain to values in the range, using the given rule. So, to find f(1/4), replace all the x's with 1/4: f(1/4) = 2(1/4)^2 + 2 Now just simplify that.
*October 30, 2015*

**college physics - incomplete**

No unique solution. 20'@90 + 3h@50 = 30+150 = 180km 1h20'@90 + 2h@50 = 120+100 = 220km 2h20'@90 + 1h@50 = 210+50 = 260km Some info is missing.
*October 30, 2015*

**Pre-Algebra, please help!**

only repeating decimals can be expressed as rational numbers. So, you are correct.
*October 30, 2015*

**Trigonometry**

the scale ratio is 3'/8" so, using that ratio on 10", you have 3'/8" * 10" = 3'*(5/4) = 15/4' = 3'9"
*October 30, 2015*

**algebra 1**

Bzzzt. but thanks for playing.
*October 30, 2015*

**algebra 1**

c is slope-intercept. The point slope form of the line through (h,k) with slope m is y-k = m(x-h) any other choices look like that?
*October 30, 2015*

**math**

well, considering that -1 = -3/3, what about -4, -3, -2,...,13 same thing. Just keep adding 1.
*October 30, 2015*

**Math**

that is 0-√3^2 = -√9 = -3 powers come first, then subtraction.
*October 30, 2015*

**Math**

looks like a G.P. with a = 4√3 r = 1/4 S = a/(1-r) = 16/√3
*October 30, 2015*

**Math**

As usual, draw a diagram. You can easily see that if you are x away from the wall, the angle of elevation of the bottom of the screen (A) is cotA = x/3 A = arccot(x/3) angle B to the top is cotB = x/10 B = arccot(x/10) So, since θ = B-A dθ/dt = dB/dt - dA/dt = -3/(x^...
*October 30, 2015*

**Math**

No, you have found cos^2 (x/2) check your half-angle formulas.
*October 30, 2015*

**Algebra**

The domain is the set of all the 1st elements of the pairs. A is the range.
*October 30, 2015*

**math**

old perimeter is 2(w+2w) so, 2(2*w+ 2w+6) = 2(w+2w)+20 Now you can find w and 2w.
*October 30, 2015*

**Calculus 1**

Sorry. I might be less grumpy if you actually showed some of that hard work. Given the info I provided above, (a) B is increasing where B' > 0, so 2/∛ - 1 > 0 2/∛x > 1 2 > ∛x 8 > x So, B is increasing on (0,8) B is decreasing on (-∞,0...
*October 30, 2015*

**Calculus 1**

why is this causing difficulties? B'(x) = 2/∛x - 1 B'(x) = 0 at x=8 as you will recall, B is increasing where B' > 0 B is concave up where B" > 0
*October 30, 2015*

**Calculus 1**

well, the derivative is 7e^-7x where is that zero?
*October 30, 2015*

**Calculus 1**

well, (e^−x)*(−e^−6x) = -e^-7x as you know exponentials have no local max/min, so the extrema are at the ends of the interval. That should pose no difficulty, if you sketch the graph.
*October 30, 2015*

**Math**

well, just keep track of the signs as you work it out. cos2x = 1 - 2sin^2x = 1 - 2*9/25 = 7/25 Or, if you insist on doing it the hard way, cos2x = cos^2x - sin^2x = 16/25 - 9/25 = 7/25 If you came up with -7/25, you need to remember your simple Algebra I!
*October 30, 2015*

**Math**

well, 6/7 of the population has just the symptoms. So, what's 6/7 of 40?
*October 29, 2015*

**math urgent help needed!!**

see the related questions below.
*October 29, 2015*

**math**

gal * miles/gal = miles so, if you know your gas mileage, just do the math.
*October 29, 2015*

**Math Pre-Algebra**

5.55% = 1/18 so, cut the cake into 18 equal squares. The cake is twice as long as it is wide, so that means cut half the cake (6 3/4 x 6 3/4) into 9 pieces, each with a side of 1/3 * 6 3/4 = 2 1/4 inches.
*October 29, 2015*

**math**

They are the points where the graph crosses the x-axis. That is, where ax^2+bx+c = 0
*October 29, 2015*

**precal**

well, the distances are 10(1/3) and 5(7/12) Then just use the Pythagorean Theorem to find the distance.
*October 29, 2015*

**@ Steve or Damon**

well, let's see. Walking an extra 12 steps took an extra 18 seconds. So, the difference in speeds is 3/2 sec/step That means that if we let w = # steps walked s = running rate, sec/step w(s+3/2) + 16s = 60 (w-12)(s+3/2) + 28s = 42 That winds up with w = (120-32s)/(2s+3) ...
*October 29, 2015*

**trigonometry**

1st leg goes (0,2*500) = (0,1000) 2nd leg goes (450sin53°,450cos53°) = (359,271) so, the plane ends up at (359,1271) The distance is thus 1321 @ E74°N
*October 29, 2015*

**math help azap**

well, your only candidates are (1)9 = 9 (3)3 = 9 (9)1 = 9 So, pick 1 or or 3 or 9 for y and see which x values work with it.
*October 29, 2015*

**Math**

ok - now what?
*October 29, 2015*

**mathematics**

b=c+6 b+c=60+8 c = 31
*October 29, 2015*

**English**

In the story "A Contribution to Statistics" 1.) Which of the following words best describes the author's view of humanity? a.) altruistic b.) optimistic c.) pessimistic d.) realistic my answer is a
*October 29, 2015*

**algebra**

23P5
*October 29, 2015*

**algebra**

n=q+6 d=n-2 5n+10d+25q = 270
*October 29, 2015*

**calculus - eh?**

as you have written it, it's not. sec(π) = -1 I think your notation is faulty. I cannot think of any manipulations that end up with that 1/π out front. Is there a derivative or integral involved somehow?
*October 29, 2015*

**algebra**

well, 5/2 = 10/4
*October 29, 2015*

**math**

all correct. good work.
*October 29, 2015*

**math**

xy=630 (x-3)(y+5)=630 You can solve that, or note that 630 = 21*30 = 18*35
*October 29, 2015*

**math**

y=c+5 If chen worked x days, y(x-3) = 180 cx = 180 I get x=12, so yang worked 9 days.
*October 29, 2015*

**maths**

lawn area = 36*15 lawn+path area = (36+2w)(15+2w) So, to find w, just solve (36+2w)(15+2w) - 36*15 = 910
*October 29, 2015*

**math**

U = b (a^2 over x^2 - a over x) or, more readably, U = b(a^2/x^2 - a/x) We can ignore b, since it does not affect where the extrema occur. It's just a scale factor. U = a^2/x^2 - a/x = (a^2-ax)/x^2 = a(a-x)/x^2 clearly the asymptote is at x=0 (asymptotes occur when the ...
*October 29, 2015*

**math**

Let's call the k's a and b just to make things more readable. S = a/x^2 + b/(20-x)^2 If a = 2b, then S = 2b/x^2 + b/(20-x)^2 Now, we can actually ignore b, since it is just a constant multiplier and will not affect where the minimum occurs. So, let's use S = 2/x^2...
*October 29, 2015*

**math**

Your function is correct. Maximum revenue is at x=0. That means that an order for 600 chairs produces the maximum revenue. This would not be the case if the discount were applied only to the excess chairs. Then the revenue would be R(x) = 600*150 + x(150-.25x) Then the maximum...
*October 29, 2015*

**math**

h^2+w^2=30^2 so h = -w+30 what? That's not correct. Now, the strength s is s = wh^2 = w(900-w^2) = 900w-w^3 so, to find the maximum strength, we need ds/dw = 900-3w^2 = 0 This is at w^2 = 300 That means h^2 = 600
*October 29, 2015*

**Pre-calculus**

clearly he means the height of the tower part of the setup. The height h of the tower is found by noting that h = 62tan45° - 62tan38° Just draw a diagram and recall your basic trig functions.
*October 29, 2015*

**Trig application**

just use the law of cosines: x^2 = 459^2 + 288^2 - 2*459*288 cos 10°
*October 29, 2015*

**Math**

If the squares have side x, then the volume is v = x(9-2x)(12-2x) = 4x^3 - 42x^2 + 108x dv/dx = 12x^2 - 84x + 108 = 12(x^2-7x+9) now just find where dv/dx=0
*October 29, 2015*

**AP CALCULUS HELP**

c'mon this is algebra I, after doing the derivatives. Just divide both sides by 2z: dz/dt = (x dx/dt + y dy/dt)/z
*October 28, 2015*

**AP CALCULUS HELP**

dividing by 2, we have zz' = xx'+yy' y' = (zz'-xx')/y not sure where you're going with this
*October 28, 2015*

**Grade 10 Math**

70/x < 1/12 x > 840 cm
*October 28, 2015*

**Geometry**

well, a rectangle has two pairs of equal sides, so AB = CD AD = BC
*October 28, 2015*

**algebra 2 A**

surely you have some ideas on some of the sections?!? A problem like this will not be assigned until after some time has been spent. Whatcha got so far?
*October 28, 2015*

**Algebra 2**

no solution. Absolute value is never negative.
*October 28, 2015*

**math**

5.696 x 10^0
*October 28, 2015*

**math**

well, 200=20*10, so how about 20*11
*October 28, 2015*

**math**

this is a standard measure. 1 section = 640 acres. Or, you can do the math, knowing other standard measures. 1mi^2 = (5280 ft)^2 1acre = 43560 ft^2 now just divide
*October 28, 2015*

**Math**

how long does it take to fall 0.91m? Find that value of t, and use it to find the velocity v = 1.03/t
*October 28, 2015*

**Parametric derivatie help plz**

first, find the slope of the tangent line at any point: dy/dx = (dy/dt)/(dx/dt) Yes, these really are fractions! dy/dx = (3cos3t)/(-2sin2t) Now, at t=pi/2, the point on the curve is (0,-1), and the slope is 0 So, our tangent is the line y+1 = 0(x-0) or y = -1 See the curve at ...
*October 28, 2015*

**geometry**

reflection across the y-axis takes (x,y) -> (-x,y) so, just flip the signs of all the x-values.
*October 28, 2015*

**Calculus**

Check your units. Their answer is in m^3, since it is 4π(20^2)(.02/100)
*October 28, 2015*

**Calculus**

v = 4/3 πr^3 dv = 4πr^2 dr so, plug in your numbers...
*October 28, 2015*

**Math**

Assuming the girls were each going to paint the same number of pots, 60x = 57(x+8) So, find x, and there were 60x pots.
*October 28, 2015*

**math**

(18 3/4)/(3 1/6) = 5 35/38 So, he can make 5 pillowcases, with some cloth left over. 5(3 1/6) = 15 5/6 So, you just need to subtract and you get 18 3/4 - 15 5/6 to find the amount left over.
*October 28, 2015*

**Pre-Calculus**

(1) well, you want 2π/5 t = π/2 and 3π/2 so, that makes t = 5/4 for the first time. Since the period is 2π/(2π/5) = 5, the second time is 5/2 later, at t=15/4 (2) from the period, this occurs at 5/4 + 5/2 k for integer k (3) just solve for t in 21cos((...
*October 28, 2015*

**math**

so, get out your graph paper and plot the points.
*October 28, 2015*

**MATH help**

you have a problem with writing points as pairs of coordinates? A = (-2,6) B = (-5,2) C = (-2,-3) Much easier to read. Now, when you get around to letting us know the rest of the points, maybe you will get some help. General polygonal shapes can always be analyzed by ...
*October 28, 2015*

**precalc**

(1) surely you know that the maximum value of sin() is 1. So, 15+42 is the max for h (2) you want sin (π/7 (t-2)) to be -1, so (π/7 (t-2)) = 3π/2 t=25/2 (3) since the period is 2π/(π/7) = 14, the max will occur at 25/2 + 14k for integer values of k. ...
*October 28, 2015*

**MATH HELP**

except, using function notation, it is f(x) = 4x-6
*October 28, 2015*

**Algebra 2**

hard to make a graph without first devising the function. Had any progress there? Hint: f(0) = 4800 f(x) drops by 600 for each increase in x.
*October 28, 2015*

**Math**

Heck, I can't even figure out what's there. ^ means what? is this supposed to be an equation? A list of numbers doesn't fit into such a scenario. Visit mindreaders.com for help with this one.
*October 28, 2015*

**Algebra**

kind of a sneaky question. The graph of g(x) is f(x)-17, so it is shifted -17 units. But the question explicitly asks how many units down f has been shifted, so the answer is 17.
*October 28, 2015*

**Math**

sinx cosy + cosx siny = sin(x+y) cosx cosy + sinx siny = cos(x-y) using the product-to-sum formulas, sinA cosB = 1/2 (sin(A+B)+sin(A-B)) so, just plug in A = x+y B = x-y
*October 28, 2015*