Saturday

November 28, 2015
Total # Posts: 35,839

**calculus**

y' = (y cosx)/(6+y^2) (6+y^2)/y dy = cosx dx 6lny + 1/2 y^2 = sinx + c y^2 + 12lny = 2sinx + c I don't see any way to express y explicitly as a function of x, using elementary functions.
*October 17, 2015*

**Algebra 2**

looks good to me.
*October 17, 2015*

**Algebra 2**

yup
*October 17, 2015*

**Math**

close. You forgot the first piece y = 40 when 0 <= x <= 500 y = 40+.05x when x > 500 I guess we can assume that negative minutes are to be disregarded as a possibility.
*October 17, 2015*

**algebra**

Assuming you meant g(x) = (5x^3 - 28x^2 - 48x)/(-8x+7) it's not a polynomial. The possible rational zeroes of the numerator include all the fractions whose numerator is a factor of 48 and whose denominator is 1 or 5. The only rational root of that is 0. Would you care to ...
*October 17, 2015*

**Algebra 2**

if the same value of x maps to more than one y, then the relation is not a function. So, check the pairs on each line. If more than one have the same 1st element, that relation is not a function.
*October 17, 2015*

**math**

actually, the length of the wire is 63.0/L = sin 45.5° the formula used by Collins gives the distance of the wire's anchor to the base of the pole.
*October 17, 2015*

**Math (sequence)**

The sequence is 1,2,3,5,8,13,21,... You already explained the logic. Each term is the sum of the two preceding terms.
*October 17, 2015*

**Calculus**

f(x) = x^3 - 2x^2 + x f'(x) = 3x^2 - 4x + 1 so, where is f' = 0?
*October 17, 2015*

**No Joy There**

I thought of that, but in that case, f(-3) ≠ f(-2), so the theorem does not apply.
*October 17, 2015*

**Calculus**

I dislike f(x). It is linear, so cannot satisfy the theorem.
*October 17, 2015*

**Calculus**

so, just do the math. Find c where f(2)-f(1) = f'(c) = 1.5 I think your function is bogus. No one would write f(x) like that.
*October 17, 2015*

**Calculus**

y(1) = ln(1)+1 = 0+1 = 1 y'(x) = 1/x so, y'(1) = 1 You want the line through (1,1) with slope 1.
*October 17, 2015*

**Calculus also need help plz plz plz**

∂z/∂x = -2x/(x^2+y^2-1)^2 ∂z/∂y = -2y/(x^2+y^2-1)^2 so, x ∂z/dx + y ∂z/dy = -2(x^2+y^2)/(x^2+y^2-1)^2 = -2z^2(1+z)
*October 17, 2015*

**Math**

really? 30 is 2 less than 32 35 is more than 40 - 6
*October 17, 2015*

**Calculus badly need help so difficult**

Assuming a typo so that the 3 %ages are in the order w,s,d: (1.02w)(0.97s)^3/(0.99d)^4 = (1.02*.97^3)/.99^4 ws^3d^4 = 0.9691 y So, y decreased by 3.09%
*October 17, 2015*

**chemistry**

sounds amazing! Oh, was there a question in there somewhere?
*October 17, 2015*

**Science**

42 cm/s
*October 17, 2015*

**Math**

There are 5^5 possible numbers There are only 5! ways to arrange the digits with no repeats. S, P = 5!/5^5
*October 17, 2015*

**logarithm**

log_2(x) = 1/log_x(2), so If log_2(x) = a and log_2(y) = b, we have 1/a + 1/b = 1/2 1/3 + 1/6 = 1/2 so, x=2^3 and y=2^6 so xy = 512
*October 17, 2015*

**Multi Cultural Psychology**

oh? and what would be the variable?
*October 17, 2015*

**maths**

If their ages are x and y, then we have x/y = 5/7 (x+4)/(y+4) = 3/4 Now just solve for x and y. It's easier if you get rid of the fractions first...
*October 17, 2015*

**math**

very few rules are Always True!
*October 17, 2015*

**MATH**

48/5 = ? 36/5 = ? Now subtract the product of those two numbers from 48*46
*October 17, 2015*

**math mtap**

How many 12x12 squares can fit in?
*October 17, 2015*

**calculus**

I interpret the somewhat garbled language as x^2 y" - 3xy' - 5y = sin(logx) well, the homogeneous equation has solution y = ax^5 + b/x Now apply the methods for the Euler equation to get the desired solution.
*October 17, 2015*

**M@them@tcs**

just use what you know about GPs: ar^3 = ar^2+72 ar^2 = ar+24 So, ar^2(r-1) = 72 ar(r-1) = 24 Now divide and you have r=3 So, a=4 and the GP is 4,12,36,108
*October 17, 2015*

**physics**

is going faster.
*October 17, 2015*

**maths**

Well, just read the words and use what you know about APs: a+2d = 5(a+5d) a+d = 2(a+3d)-3 Now you can find a and d and answer any other questions about the sequence.
*October 17, 2015*

**Math**

Six times a number less than ten So, is that (Six times a number) less than ten: 10-6x=8 or Six times (a number less than ten): 6(10-x)=8 ? Either way, it's not 3 You solved 6x-10 = 8 x<15 allows for negative hours. Bzzzt. The reasonable choice is thus 0 <= x <= ...
*October 16, 2015*

**Calculus**

you need two things: x^2+c = 4x+3 (curve intersects line) 2x = 4 (slopes match up) Now it's easy to find c, right?
*October 16, 2015*

**Math**

(a) even power, negative coefficient means heading down on both sides. (b) what are the factors of 100? (c) between 1st two real roots and the last two roots. Or, between the two real roots of there are only two. (d) do you have calculus to use? N declines where N' < 0...
*October 16, 2015*

**Calculus**

Since the cost is the same for all surface areas, we just want to find the box with minimum surface area that holds the given volume. The surface area involved is one base and two short sides and two long sides, so a = 2x^2 + 2xz + 4xz = 2x^2+6xz But since z = 36000/2x^2 = ...
*October 16, 2015*

**maths**

2x^2+18x+14 2(x^2+9x+7) This does not factor. There are no factors of 7 that add to 9. Use the Quadratic Theorem if you want to find the roots, but is does not factor using integers. Since the roots are (-9±√53)/2 It factors as 2(x-(-9-√53)/2)(x-(-9+√...
*October 16, 2015*

**math**

As always, draw a picture. The radius of the circle is the slant height of the cone. The arc length of the paper is the circumference of the cone. So, the cone's slant height is 13 The circumference of the cone is 10π So, the angle θ of the sector is found using ...
*October 16, 2015*

**math**

If the wind speed is <x,y> then you have <180 sin15°,180 cos15°> + <x,y> = <150,0> Now you can find x and y, and thus the speed and direction.
*October 16, 2015*

**Integral**

There is no way to do this integral in terms of the elementary functions. There are a bunch of special functions which wolframalpha uses to evaluate weird problems like this, but even those fail. The only way to handle it is if you have a definite integral, and then you can ...
*October 16, 2015*

**Math**

just keep track of the units: (3/8 mi) / (1/16 gal) = 6 mi/gal
*October 16, 2015*

**Adamson University Math**

depends. what is the combustion reaction?
*October 15, 2015*

**algebra**

I hope you meant $.09 per extra minute. Seems kinda harsh to make the 1st minute cheaper. 50+9*(10-1) = ? At any rate, you apparently have trouble with decimal numbers.
*October 15, 2015*

**phy**

Since it takes the same time to rise as it does to fall, how long does it take to fall 7.9 meters? 4.9t^2 = 7.9 Use that value of t to see how fast (horizontally) you have to move to cover 9 meters in that time. v = 9/t
*October 15, 2015*

**math**

total fence: 2(25+5) = 60 60/2 = 30
*October 15, 2015*

**Math**

If the print is x by y, then the page is (x+2)(y+4) Since xy=30, we want to minimize a = (x+2)(30/x + 4) = 4x+8 + 60/x So, find x when da/dx = 0 to get the minimum area.
*October 15, 2015*

**Algebra**

well, the people who do get tuxes satisfy 20 <= 1.2x <= 40 So, solve that for x and then take everything else.
*October 15, 2015*

**Geometry**

since you provide no information about the diagram, the angles, etc., I hope you do not expect any helpful responses. google is your friend. Try doing a little work on your own...
*October 15, 2015*

**algebra 1**

c and d would be very unwieldy. However, you do know (I hope) that 60 mph = 88 ft/s That's probably a good conversion to use.
*October 15, 2015*

**OPT MATHS**

Or, in more usual notation, (1+cos π/8)(1+cos 3π/8)(1+cos5π/8)(1+cos7π/8) = 1/8 cos 7π/8 = -cos π/8 cos 5π/8 = -cos 3π/8 So, you want (1+cos π/8)(1-cos π/8)(1+cos 3π/8)(1-cos 3π/8) = sin^2(π/8) sin^2(3π/8) ...
*October 15, 2015*

**Integral Calculus**

y' = y^2-5y+6 dy/((y-3)(y-2)) = dx dy (1/(y-3) - 1/(y-2)) = dx ln[(y-3)/y-2)] = x + c (y-3)/(y-2) = c e^x y(0) = 1, so (1-3)/(1-2) = c c = 2 (y-3)/(y-2) = 2e^x Now you can rearrange things and find y as a function of x: y = (3-4e^x)/(1-2e^x)
*October 15, 2015*

**Bmcc**

so, what volume of water does it displace if submerged?? How much mass is that?
*October 15, 2015*

**Math**

remember your Pythagorean Theorem? x^2 + 7^2 = 9^2 Now just find x
*October 15, 2015*

**Pre-Algebra**

Looks good to me.
*October 15, 2015*

**maths**

If the rate was r, then 7.5r + (11-7.5)(1.5r) = 112
*October 15, 2015*

**Math**

how do you figure such a thong? If I ask how many times more is 12 than 3, you divide 12/3, right? So, 4/5 is (4/5)/(1/3) = 12/5 as big as 1/3. After all, 4/5 = 12/15 1/3 = 5/15 and 12 is 12/5 as big as 5.
*October 15, 2015*

**science- physics**

first, figure how long it takes to fall 1.1 meters. s = 4.9t^2 Then, using that t, figure how far horizontally the travel, since s = vt Naturally, since B's speed is 1/3 of A's, it will travel 1/3 as far, since both balls take the same time to drop to the floor.
*October 15, 2015*

**Calc 1**

no ideas at all? Maybe the Pythagorean Theorem? The distance z is z^2 = x^2+y^2 2z dz/dt = 2x dx/dt + 2y dy/dt or z dz/dt = x dx/dt + y dy/dt Remembering your good old 3-4-5 right triangle, you can see that z=5 when x=3 and y=4. Now, you have all the numbers you need to find ...
*October 15, 2015*

**Maths:distance covered urgently need help**

you must know that distance = speed * time. So, just use that! 35min @ 60 km/hr = 35km So, since 1:15 = :35 + :40, he drove for 40 min at 60 km/hr, retracing his route for 40 km. So, 35km wrong way, 40 km right way, leaves him 5 km on his way to his destination. When you get ...
*October 15, 2015*

**Calc 1**

just use the good old chain rule. By now that shouldn't be causing any difficulties, eh? If y = e^u, y' = e^u u' y = e^(sinh(x)) y' = e^sinh(x)) * cosh(x)
*October 15, 2015*

**Calc 1**

good old product rule. Don't let the trigh functions scare you. y = x^3 tanh(5x) y' = 3x^2 tanh(5x) + x^3 (5sech^2(5x))
*October 15, 2015*

**like, chemistry, maybe?**

or heck, even a real subject, rather than a list of schools.
*October 15, 2015*

**Calc 3**

The parametric equations for the circle are x = 4cos t y = 4sin t so, the curve of the intersection also includes z = 5-x-y = 5-4cost-4sint Now, the curvature of the curve described is k = |dT/ds| = |dT/dt| ÷ |dr/dt| at (0,4,1), t = π/2 r = <4cost,4sint,5-4cost-...
*October 15, 2015*

**Mathematics - eh?**

is there a question in there somewhere? and maybe a little more information?
*October 15, 2015*

**secab**

no such thing. scalar product is a binary operation on only two vectors, producing a scalar value. You could do (a•b)*(c•d) but that's something different.
*October 15, 2015*

**science**

since it's an adjective, that's not likely. However a polyatomic substance, having more than one kind of atom, would indeed be a compound. They're usually ions, rather than balanced molecules.
*October 15, 2015*

**Maths**

Doing your division, I get a remainder of -72, so x+3 is not a factor. I found that x^3-4x^2+x-6 has no rational roots at all! So, I suspect a typo in the problem, if you were expected to factor it. I did find that x^3-4x^2+x+6 = (x+1)(x-2)(x-3)
*October 15, 2015*

**Algebra**

so, use your function. what is your function, by the way?
*October 15, 2015*

**Algebra hw, coordinates!! help!!**

as you recall, reflection over the x-axis takes (x,y) -> (x,-y) So, just change the sign of all the y-values.
*October 15, 2015*

**Algebra**

No idea. Sounds ok, but I don't have the relationship at hand.
*October 15, 2015*

**math, PLEASE HELP!**

What can I say? I worked your two problems, even gave you the answers. i think you'd better google rotations and read the many examples that will pop up. I repeat. Get out your string and holding one end at (0,0), place the other end at various places and ROTATE IT! Just ...
*October 15, 2015*

**math, PLEASE HELP!**

You know, you can just take a piece of graph paper, and stretch a string from (0,0) to (-2,0) and then rotate the end. You can easily see that (0,-2) -> (-2,0) For this one, (-3,5) -> (3,5) So, using your string, you can see that the point was rotated 180°.
*October 15, 2015*

**Calculus - eh?**

As always, draw a diagram. Label the water works W. It sounds like C,W,D are in a straight line. If so, there is really very little calculus involved here. In fact, the least cost pipeline is to build it right at D. If C and D are x miles apart, and W is y miles from C, then ...
*October 15, 2015*

**maths**

f + (3f+2) = 102
*October 15, 2015*

**Science**

Since the only atoms involved are H2O, the gases are clearly hydrogen and oxygen. Since the water was changed into different compounds (in fact, elements), a chemical change took place. I expect you can check the boiling points of H2 and O2 to confirm the deduction.
*October 15, 2015*

**maths**

If the number is xy, then x+y=12 10x+y = 36+10y+x Now just find x and y. If that's too hard, just think of the pairs of digits that add to 12, and try them out.
*October 15, 2015*

**math**

If A takes x hours, and B takes x+6 hours, then we have 1/x + 1/(x+6) = 1/4 Now just find x, and then x+6.
*October 15, 2015*

**precal**

Pretty lousy account if it does not accrue interest. Anyway, just look up your formula for annuities, and plug in your numbers. Or check the related questions below. Or (gasp) give google a try.
*October 15, 2015*

**Math**

Assuming you meant (13-15x^2)/((x^2-1)(x+3)) then you get (1/2)/(x+1) - (1/4)/(x-1) - (61/4)/(x+3) If you mean x-3, then just make the fix. I trust you just wanted confirmation of your work, eh? If not, and you got stuck, how far did you get?
*October 15, 2015*

**Area of a triangle**

have you considered the angle bisector theorem, and the law of sines?
*October 15, 2015*

**Algebra 2**

come on, this is just Algebra I all over again. From the first equation, x = 17-2y Plug that into the 2nd equation and you have 17-2y-y=2 -3y=-15 y=5 Or, from the 2nd equation, x=y+2, so y+2+2y=17 3y=15 y=5 Or, just subtract the 2nd from the first, and you get 3y=15 y=5 In any...
*October 14, 2015*

**Algebra 2**

clearly, since you are given the slope and the y-intercept, the best representation is the slope-intercept form! y = 4x-6 You can massage that any way you like.
*October 14, 2015*

**Math🤓**

Assuming a rectangular field, total fence: 32+40+32+40 = 144 ft 144/4 = 36
*October 14, 2015*

**Maths**

w=3d (w-6)+(d-6) = 36 (3d-6)+(d-6) = 36 4d=48 d=12
*October 14, 2015*

**Math**

I like C, since there are 140/200 of the students with A or B blood.
*October 14, 2015*

**PreCalculus**

plug in your numbers: h(t) = -16t^2 + 4t + 10 Recall from your Algebra I that this is just a parabola, with vertex at x = -b/2a, or in this case, x = 1/8 h(1/8) = 41/4 This is no time to forget your earlier math!
*October 14, 2015*

**Calculus**

Using the Pythagorean Theorem from your Algebra I days, the distance to the plane, z, after the plane has gone x miles since being directly overhead, is z^2 = 2^2 + x^2 we want the rate at which the distance is changing, dz/dt. So, taking derivatives, and remembering the chain...
*October 14, 2015*

**Geometry**

since vertical angles are equal, and supplementary angles add to 180, if the vertical angles have measure x, then x+x = 180
*October 14, 2015*

**Math - PS**

My bad! 4 is not in the list. So, the sum is just zero.
*October 14, 2015*

**Math**

you want the sum of the integers from -3 to 4 they will be -3,-2,-1,0,1,2,3,4 Clearly the sum is just 4, since all the + and - pairs add to zero.
*October 14, 2015*

**Statistics**

for Z=-0.25, that is .25 std below the mean, or 62 - 0.25*12 = 62-3 = 59 Same for the others.
*October 14, 2015*

**maths**

mixed numbers are a pain. You have to convert them to fractions to do much with them. So, you have (83/12)÷(46/5)*(12/8) = (83/12)(5/46)(12/8) = (83*5*12)/(12*46*8) = 415/368 or 1 47/368
*October 14, 2015*

**MATH**

recall your 3-4-5 right triangle. Multiply each side by 0.7 and you choice (A). Or, you can just square all these numbers and see which two add up to the third in any given choice.
*October 14, 2015*

**Infinity series i need help also**

a = 20 r = 3/5 S = 20/(1 - 3/5) Better review you geometric series material.
*October 14, 2015*

**math**

the like terms are those involving the same variable, in this case, y So, (A)
*October 14, 2015*

**MATH**

pick the one where no x-value (1st element) is repeated. Sadly, not D. You cannot have f(5) = 4 and also f(5) = 1.
*October 14, 2015*

**Maths**

g(0) = (-1)(2)(-a)(-b) = -2ab g(3) = (2)(5)(3-a)(3-b) (3-a)(3-b) = 4 9-3a-3b+ab = 4 9-3(a+b)-2 = 4 -3(a+b) = -3 a+b = 1 (a+b)^2 = a^2+b^2+2ab = a^2+b^2-4 = 1 a^2+b^2 = 5 Now it should be clear what a and b are.
*October 14, 2015*

**math**

well, work = force * distance, so ...
*October 14, 2015*

**MATH**

1A 2B 3C 4B
*October 14, 2015*

**Math**

I guess you do. -^90 is pure garble. If you have an exponent, it goes in between the numbers, as PsyDAG showed you.
*October 14, 2015*

**MATH**

well, let's see 1=√1 2=√4 3=√9 4=√16 5=√25 So, do you still think √6 is between 4 and 5?
*October 14, 2015*