Wednesday

November 25, 2015
Total # Posts: 35,789

**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*

**Math**

A⊆B is clearly false, since 7 is not an element of B B⊆U is trivially true, since U is the universe containing all sets under analysis.
*October 28, 2015*

**math please help**

no, (-5)/(-5) = 1 so, divide both sides by -5 and you have x = -35/-5 = 7 check: -5*7 = -35 Don't forget your basic arithmetic now that you're doing algebra.
*October 28, 2015*

**math please help**

well, -5/-5 = 1, so ...
*October 28, 2015*

**math help azap**

this is a joke, right? subtract 15 from both sides.
*October 28, 2015*

**Math**

find the angle between the two directions, then use the law of cosines.
*October 28, 2015*

**Algebra**

assuming all the hoses have the same fill rate, 3 hoses fill 5000gal/hr, so that is 5000/3 gal/hr per hose. now you know the hose fill rate, so multiply that by 4, and divide it into 15000gal.
*October 28, 2015*

**maths**

plot the points and then use the usual distance formula.
*October 28, 2015*

**Math**

If the brakes are good enough, they'll never touch. Otherwise, they'll hit at some speed up to 115 mi/hr. and what is an "empack"?
*October 28, 2015*

**Calculus - Differentiate**

just use the quotient rule: y' = (cosx)(x^4) - (sinx)(4x^3) ------------------------------ = (x cosx - 4sinx)/x^5 x^8
*October 28, 2015*

**Math**

Looks good to me.
*October 28, 2015*

**11th grade math**

y^(a-b)
*October 28, 2015*

**San Jose city college**

The upwind speed is 100 mi/hr, and the downwind speed is 120 mi/hr. So, if the plane's speed is p and the wind speed is w (clearly, from the west), p+w = 120 p-w = 100
*October 28, 2015*

**math**

I think you'd be better off with r^4 s
*October 28, 2015*

**alegbra**

It will take x years, where e^(.1175x) = 3
*October 28, 2015*

**Math**

close enough.
*October 28, 2015*

**GOA**

4.9(20/300)^2
*October 28, 2015*

**Maths**

If the digits are t and u, then its value is 10t+u. So, 10t+u = 7u-8 10u+t = 10t+u-9 I don't get an integer solution. Check my interpretation of the text.
*October 28, 2015*

**Algebra**

.4x = 1200 x = 1200/.4
*October 28, 2015*

**calculus**

42.00
*October 28, 2015*

**math**

since the water is already 9 cm deep, another 11 cm must be added. So, the water added is 50*30*11 - 25*25*11
*October 28, 2015*

**math**

72 is the total apples in all 3 baskets. They already listed how many of each kind in the baskets.
*October 28, 2015*

**Math**

log_5(x^2) + 4log_5(x) = 12 2log_5(x) + 4log_5(x) = 12 6log_5(x) = 12 log_5(x) = 2 x = 5^2 = 25
*October 28, 2015*

**Calculus**

y = x^4 dy = 4x^3 dx = 4*1(1/2) = 2 Δy = f(x+Δx)-f(x) = (1+1/2)^4 - 1^4 = 81/16 - 1 = 65/16 = 4.01625 They are nowhere near the same. This is because dx uses a linear approximation (the tangent line at x=1), but the actual graph curves steeply upward. See the graphs ...
*October 28, 2015*

**Math**

well, did you not just plug in the points given? g(1/4) = -9, so -2a+k = -9 g(16) = -6, so 4a+k = -6 a = 1/2 k = -8 g(x) = 1/2 log_2(x) - 8
*October 28, 2015*

**Physics, science**

total distance: 45+2*78 km total time: 3 hr that help?
*October 27, 2015*

**Calculus**

recall that lim (1+1/n)^n = e n->∞
*October 27, 2015*

**Calculus**

so, how do you figure the distance? Look up the various measurements of a ball field. Then just take the derivatives and plug in your numbers.
*October 27, 2015*

**maths**

unless they form a closed area, where the 1st and last posts are the same. Then it's back to 15.
*October 27, 2015*

**Dallas can**

2000 * e^(3*.051) just use the formulas you have been studying.
*October 27, 2015*

**College Algebra**

F = kv^2/r That means that Fr/v^2 = k, and is constant. So, you want F such that F*10/20^2 = 300*5/15^2
*October 27, 2015*

**Trig**

If the angle you want is a, and the 3rd angle is b, then by the law of sines, 1250/sin53 = 1500/sinb But, a+b+53=180, so b=127-a sin(127-a) = 1500sin53/1250 = 0.9583 so, 127-a = 73.4 a = 53.6 I'll let you decide whether there is a second possibility.
*October 27, 2015*

**Algebra 2**

-4|t-2| - 9 = -37 -4|t-2| = -28 |t-2| = 7 so, which numbers are 7 away from 2? t = 9 or -5 more rigorously, either (t-2) = 7 t=9 or -(t-2) = 7 -t+2 = 7 t = -5
*October 27, 2015*

**precalc**

clearly 2x = pi/6 tan(x+pi/2) = -cot(x) 3sec(x-pi/4) = 6 sec(x-pi/4) = 2 cos(x-pi/4) = 1/2 x-pi/4 = pi/3 now just look in all the quadrants that work.
*October 27, 2015*

**Math**

agree an even multiple of any integer is always even
*October 27, 2015*

**Math**

assuming you mean y=2log_5(x)-7 reflected it is y = -2log_5(x)+7 shifting up you just add 6: y = -2log_5(x)+13
*October 27, 2015*

**calculus**

correct
*October 27, 2015*

**Math**

add 'em up and divide by 4.
*October 27, 2015*

**Maths**

seems pretty clear to me. Just double all the numbers.
*October 27, 2015*

**Math**

so, use the formulas - what's the problem?
*October 27, 2015*

**Precalc**

3s+c = 71 a = √3/4s^2 + c = √3/4 s^2 -3s + 71 da/ds = √3/2 s - 3 clearly a is minimum when s = 2√3 so, the circumference c is 71-6√3
*October 27, 2015*

**science**

distance = speed * time
*October 27, 2015*

**Federal polytechnic, oko**

a = (104m/s)/(10s) = 10.4 m/s^2 F = ma now go for it.
*October 27, 2015*

**Maths**

type in your function at wolframalpha.com
*October 27, 2015*

**11 Grade Math-Based Physics**

#1 Lose the apostrophes 1a, 1b look good 1c cannot be right, since m/s is not acceleration. #2 all ok #3 is (a) - speed has no direction. (c) is for velocity #4. Not sure what 60° NE means. I know N 60° E and E 60° N. In any case, draw the direction and take the ...
*October 27, 2015*

**physics**

find the speed of sound. If it is x m/s, then you have two equal distances. The distance fallen is s = 5t^2, so the falling time is √(s/5) The sound takes s/x seconds to come back. √(s/5) + s/x = 3 So, look up x and do the math for s, the well depth. The rest then ...
*October 27, 2015*

**Math**

((6/7)/2)/3 = 1/7
*October 27, 2015*

**PHYSICS**

As always, draw a diagram. use the law of sines AC/sin50° = 100/sin70°
*October 27, 2015*

**maths 3 advanced**

ignoring all those pesky zeros, we can set up the ellipse as follows: center of earth at (0,0) perigee at (-8,0) apogee at (16,0) center at (4,0) so, the equation is (x-4)^2/a^2 + y^2/b^2 = 1 plugging in our points, we have 144/a^2 + 0 = 1 a = 12 a^2-c^2 = b^2 b^2 = 12^-4^2 = ...
*October 27, 2015*

**maths**

500 what? pages? seconds? How about asking an actual question instead of just mumbling at the end?
*October 27, 2015*

**Physics**

It sounds like you mean period ∝ L^(3/5) v ∝ L/T = L/L^(3/5) = L^(2/5)
*October 27, 2015*

**Math 3**

y = 1/21 (x-3)^2 (x+7) y' = 1/21 (x-3)(3x+11) That help?
*October 27, 2015*

**physics**

find t when h=0. h(t) = 95+10t-4.9t^2
*October 26, 2015*

**Geometry**

well, you give no relationship among the angles, but one possible avenue is to assume that 2x + x-5 = 100
*October 26, 2015*

**Math**

it hasn't been simplified at all. You did, however, correctly apply the distributive property to remove the parentheses. Many people consider factoring out common values to be simplification. In that case, I'd have to say that factoring out another p, giving 2p^2q(3-q^...
*October 26, 2015*

**Math**

your question kind of got garbled on the way. I can tell you that the speed of a point on the wheel is 60πcm/rev * 5rev/s = 300π cm/s do with that what you will
*October 26, 2015*

**math**

between $1000 and $2000 1xxx a multiple of 10 1xx0 hundreds digit is 30 times the value of the tens digit 1620 ..40 not possible, or 30x would be too big
*October 26, 2015*

**CALCULUS TEST TOMORROW**

well, just do the math 1/R = 1/R1 + 1/R2 plug in R1 and R2 to find R 1/R^2 dR/dt = 1/R1^2 dR1/dt + 1/R2^2 dR2/dt Now just plug in your numbers to find dR/dt
*October 26, 2015*

**Calculus**

∫[0,1] ∫[-√(x-x^2),√(x-x^2)] √(x^2+y^2) dy dx Or, you might find things easier in polar coordinates.
*October 26, 2015*

**algebra**

where did you get 300W? If there are two short sides (x) and one long side (y), then 2x+y = 300 a = xy = x(300-2x) = 10450 Now solve that for x, the short side.
*October 26, 2015*

**Calculus plz help integral**

It appears you want ∫[0,1/2] √x e^x dx if you let x = u^2 dx = 2u du then you have ∫[0,1/√2] u e^(u^2) * 2u du = 2∫[0,1/√2] u^2 e^(u^2) du Hmmm. Not much better. These involve the err function, so unless you have a table of that handy, you&#...
*October 26, 2015*

**Calculus help**

x^(1/3) + (xy)^(1/3) = 4y^2 1/3 x^(-2/3) + 1/3 (xy)^(-2/3) (y + xy') = 8yy' Now just solve that for y'. There are several ways to massage the final answer.
*October 26, 2015*

**Math**

#5. ok #6. ok #7. ok, assuming a typo in the question. #8. ok
*October 26, 2015*

**algebra**

Can you solve q = p(5) for p?? If so, do the same step for this one.
*October 26, 2015*

**Geometry Rectangle**

With two short sides (x) and one long side y, 2x+y = 100 The area is a = xy = x(100-2x) So, you just need to solve x(100-2x) = 1200 2x^2-100x+1200 = 0 2(x-20)(x-30) = 0 now can you figure it out?
*October 26, 2015*

**Math 1350**

If BC is x, then 2x + x + x+10 = 58 x = 12 AC = AB+BC = 2x+x = 36
*October 26, 2015*

**Geometry:Rectangles**

If the width is x, then the length is 100-2x. SO, the area is x(100-2x) = 1200 2x^2 - 100x + 1200 = 0 x^2 - 50x + 600 = 0 ...
*October 26, 2015*

**Math**

wow. That's some mistyping of "like terms in"! There are two y terms, so (A)
*October 26, 2015*

**math**

well, two sides are x and x+2 I have no idea what half of the sum of the longest side might mean. A sum involves the addition of two numbers.
*October 26, 2015*

**Math**

nope. That's the only certainly wrong choice. So, given that one of the other three is correct, which one is it?
*October 26, 2015*

**Math**

3.50 n >= 140.00
*October 26, 2015*

**Treasure!**

Look in Mt Doom. It's right next to the One Ring!
*October 26, 2015*

**maths**

clearly, x=1 and y=1 is a solution. It is clearly the only solution, since using any other natural numbers (which are positive integers) produces 2x+5y which is greater than 7. If you include all real numbers, the graph is a line, and any point on the line is a solution. It ...
*October 26, 2015*

**Precalculus**

I assume you can find the normal trig angle associated with the point. For an angle θ, measured clockwise, the bearing is 90+θ. Just plot the point and note how many degrees clockwise from vertical it is. That is the compass heading.
*October 26, 2015*

**math**

clearly the ratio of each smaller square is 1/√2. So, you have a geometric progression with a = 8 r = 1/√2 Now just apply your formulas for the sum of such a sequence.
*October 25, 2015*

**Calculus**

If the final box has bases x^2 and height h, then v = x^2 h and we also have x^2 + 4xh = 100, so h = (100-x^2)/4x That means v = x^2 (100-x^2)/4x = x/4 (100-x^2) = 25x - 1/4 x^3 dv/dx = 25 - 3/4 x^2 maximum volume is achieved when dv/dx=0.
*October 25, 2015*

**Calculus**

divide the fencing equally among lengths and widths.
*October 25, 2015*

**Algebra 2**

so, did you make a graph?
*October 25, 2015*

**Calculus**

google is your friend. lots of examples online. you looking for solids of revolution, or 3D volumes in general?
*October 25, 2015*

**Calculus @Damon**

oh yeah - Good catch
*October 25, 2015*

**Calculus**

consider the population as a collection of rings of thickness dr. Each ring's population is the area of the ring times its density. Add them all up and you get p(r) = ∫[0,7] 2πr*5(5+r^2)^(1/3) dr for the insects, dp/dt = 280 + 8t + 1.5 t^2 p(t) = 40 + 280t + 4t^...
*October 25, 2015*

**Math**

if he starts at (0,0), then he winds up at (8,4). So, he is then √80 miles from home.
*October 25, 2015*

**math**

well, 2/3 = 0.66666 which is greater than any of the other numbers I have no idea what the desired inequality is supposed to be.
*October 25, 2015*