oobleck

Most popular questions and responses by oobleck
  1. Geography

    There's 300 miles of air pushing down from above, right?

    posted on May 22, 2019
  2. Math

    1 hour that's what you said, right?

    posted on May 22, 2019
  3. Math

    42

    posted on May 22, 2019
  4. Maths

    dx/dy = (dx/dt)/(dy/dt) (cost - t sint)/(1+cost) d^x/dy^2 = d/dy (dx/dy) = d/dt (dx/dy) dt/dy = (d/dt (dx/dy))/(dy/dt) = -(sint(t sint+2) + t cos^2(t) + cost(t+sint))/(1+cost) at t = pi/2 that is -(pi/2 + 2)

    posted on May 22, 2019
  5. math

    If the width is w, then we know that (12+2w)(9+2w) - 12*9 = 100 Now just find w.

    posted on May 22, 2019
  6. General Calculus

    if that confuses you, just recall the quotient rule for derivatives, and implicit differentiation.

    posted on May 21, 2019
  7. General Calculus

    you know that tanθ = y/x sec^2θ dθ/dt = (x dy/dt - y dx/dt)/x^2 so just plug in your numbers.

    posted on May 21, 2019
  8. algebra

    or just leave it as 1/6 That is the exact answer. Using a decimal value will only give an approximation. Don't feel you always have to use decimal values, unless they are requested. Probabilities are often expressed as fraction.

    posted on May 21, 2019
  9. Math

    if it depreciates by 5.1%, that means that each year its value is 94.9% what it was the year before. So, after 8 years, the value is 9250 * 0.949^8 = 6085.15

    posted on May 21, 2019
  10. math

    Recall that if the angle x subtends two arcs A and B, with A > B, then x = 1/2 (A-B)

    posted on May 21, 2019
  11. Maths

    just find h such that π/3 (15/2)^2 * 12 = π*(10/2)^2 h that is, 225π = 25π h

    posted on May 21, 2019
  12. Math

    is every number greater than one? No. Think a little more on it.

    posted on May 21, 2019
  13. Matrice Equation

    In that case, ya got me. Not sure how you would go about converting the matrix to a form involving just 1's and 0's. Maybe you could clarify a bit... What does the problem actually say? You need to use row manipulations (elimination) to get something on

    posted on May 21, 2019
  14. Matrice Equation

    two matrices one matrix Not sure what you so with symbolabs, but to solve the equation AX = B you multiply on the left by A-1, giving X = A-1B See it written out at

    posted on May 21, 2019
  15. Math

    you got the first one, but missed the other two. 12+4m = 24 4m = 12 m = 3 d-6 > -4 d > 2 Note that this one does not have a single answer. ANY number greater than 2 will make the sentence true. You solved the equation d-6 = 4

    posted on May 21, 2019
  16. Maths

    well, 7x4 = 28 maybe you can take it from there.

    posted on May 21, 2019
  17. math

    well, one ratio is clearly 31:7 there are others possible, depending on what it is you're comparing.

    posted on May 21, 2019
  18. maths

    just use the definition of even/odd even: f(-x) = f(x) odd: f(-x) = -f(x) It may be neither, ...

    posted on May 21, 2019
  19. Math

    54=9*6, so 7:9 = 7*6 : 9*6 = 42:54

    posted on May 21, 2019
  20. chemistry

    so, what is the volume of a lead atom? what is the mass of a lead atom? How are they packed? Since the crystal lattice affects density on a large scale, maybe you just want the density of a single atom. In any case, density = mass/volume

    posted on May 21, 2019
  21. Math

    sorry, @Arya better try again

    posted on May 21, 2019
  22. physics

    an LED on your computer a 50,000 ton diesel locomotive

    posted on May 21, 2019
  23. Math

    x + 8 = -20 right - check your work >wink wink< hmmm. I don't see any ...

    posted on May 21, 2019
  24. Maths

    complete the squares and it becomes clear: 36x^2+36y^2-24x-36y-23=0 36x^2-24x + 36y^2-36y = 23 36(x^2 - 2/3 x) + 36(y^2-y) = 23 36(x^2 - 2/3 x + 1/9) = 36(y^2 - y + 1/4) = 23 + 36(1/9) + 36(1/4) 36(x - 1/3)^2 + 36(y - 1/2)^2 = 36 (x - 1/3)^2 + (y - 1/2)^2

    posted on May 20, 2019
  25. Math

    that was mean? I merely suggested what might lead you to the correct answer, since your choice was wrong.

    posted on May 20, 2019
  26. Maths

    Just add up all the weights if there are g girls, then you know that 55*8 + 48g = 50.8(8+g) Now just solve for g

    posted on May 20, 2019
  27. Math

    I think you need to review what an integer is. and what those three dots ... mean

    posted on May 20, 2019
  28. Science

    all look good.

    posted on May 20, 2019
  29. Math

    well, all absolute values are positive all positives numbers are greater than any negative number. With that, you can pick the right choice(s). As written, there are two. So, if you only get one choice, there's a typo somewhere.

    posted on May 20, 2019
  30. Chemistry

    nice try. tell me your answer, and I'll check it out.

    posted on May 20, 2019
  31. Chemistry

    the balanced equation is 4Al + 3O2 = 2Al2O3 so, how many moles of Al do you have? You get half that many moles of Al2O3 now convert back to grams

    posted on May 20, 2019
  32. chemistry

    assuming you retain constant temperature, PV=kT remains constant. So, you just need to find P such that P*5 = 1*7.5

    posted on May 20, 2019
  33. Math

    that would be 500(1 + 0.045*3) = _________

    posted on May 20, 2019
  34. Physics

    1A = 1C/s so, how many electrons in 600 seconds? How many electrons per molecule deposited? Now you can figure the # molecules, and thus the # moles, and thus the mass

    posted on May 20, 2019
  35. Math

    formula for area of parallelogram is, of course, area = base * height

    posted on May 20, 2019
  36. Physics

    Let A's initial velocity be in the + direction (to the right) If the two initial velocities are Va and Vb, then to conserve momentum we need .25Va + .35*0 = .25(-0.12) + .35(0.65) solve for Va Now you can figure the total KE (1/2 mv^2) before and after

    posted on May 20, 2019
  37. physics

    that would be 5(1,0,-1)+2(1,2,1)+3(1,-1,-3) = (10,1,-12)

    posted on May 20, 2019
  38. Chemistry

    how many moles HCl available? how many moles KOH was used? each mole of KOH neutralized 1 mole of HCl Now, knowing how many moles of HCl are left, it will take that many moles of NaOH, so convert that to ml of .02M NaOH.

    posted on May 19, 2019
  39. Maths

    area = 2pi*r(r+h) so, plug in your numbers and solve for h

    posted on May 19, 2019
  40. math

    for every 2 girls, there are 3 boys to choose from 2/5 of 20 is 8

    posted on May 19, 2019
  41. Calculus

    Yeah, I thought of that, and you're probably right. You should talk to your teacher and ask what they meant by "critical" values. When we're talking calculus, that has a certain special meaning, not just "values of f'(x)"

    posted on May 19, 2019
  42. Physics

    volume = area * thickness now just plug in your numbers

    posted on May 19, 2019
  43. math

    surely that would be 1/6

    posted on May 19, 2019
  44. Calculus

    #2 ok #3 my bad - you are correct #5 me too. the nonzero values for f'(x) confuse me. #6 yes. That is only an approximation over an interval #8 we have dy/dx = 2f'(g)*g' so, using the product rule where y' = u*v y" = 2(f"(g)*g')*g' + 2f'(g)*g" =

    posted on May 19, 2019
  45. maths

    even if f(-x) = f(x) odd if f(-x) = -f(x)

    posted on May 19, 2019
  46. math

    area = base + 4 faces, right?

    posted on May 19, 2019
  47. maths

    consider f(z) = e^z. then e^(x+y) = e^x e^y then g(x) = e^x/(1+e^2x) is that even or odd, or neither?

    posted on May 19, 2019
  48. maths

    The axis of reflection will be midway between the two lines, right? These two lines intersect at (6,15) The axis must have y-intercept at (0,6) So, now just find the line through those two points.

    posted on May 19, 2019
  49. Calculus

    #1 I get 40. How did you get 24? #2 recall that e^(lnx) = x So, you have f(x) = (x^3+5)^2 Now what is your answer? You have just said that d/dx e^u = e^u, but you forgot the chain rule. #3 That's not what I get. Let u = 1+sinθ and you have ∫ du/√u #4

    posted on May 19, 2019
  50. physics

    well, the height at time t is h(t) = 0 + 60 sin42° - 4.9t^2 assuming it is hit from a height of 0 (unusual for a baseball...) anyway, if needed plug in the initial height and then just work with the quadratic function the way you remember from Algebra I

    posted on May 19, 2019
  51. pre algebra

    9*19z + 9*4

    posted on May 19, 2019
  52. Maths

    b-3 = 192-b 2b = 195 b = 195/2 so, a = 3 - 195/2

    posted on May 19, 2019
  53. Chemistry

    Looks like it takes 5 moles of O2 to react with 1 mole of propane. So you will need 15 moles of O2. convert that to grams.

    posted on May 18, 2019
  54. calculus

    for n>1, n^(-2/3) > 1/n, which sum diverges

    posted on May 18, 2019
  55. geometry

    I see a line segment BD, adjacent to a 3-4-5 triangle, DCE Better ask a question and/or 'splain things better.

    posted on May 18, 2019
  56. Math

    yes, b+10 = p But also, p+5 = 2e Not sure who the heck Ellis is, but if you meant Bob, then we have p+5 = 2(b+5) or, rearranging things, p - 2b = 5 p - b = 10 subtracting, we get b = 5 So, Bob is 5 and Peggy is 15 In 5 years, they will be 10 and 20

    posted on May 18, 2019
  57. math

    hint: what is h(0)?

    posted on May 18, 2019
  58. math

    well, the garden measures (in posts) 6x2, so now just figure the perimeter (in posts)

    posted on May 18, 2019
  59. Math

    x = k + by You know that 30 = k + 2b 50 = k + 6b Now just solve for k and b, and you can answer the questions

    posted on May 18, 2019
  60. math

    42

    posted on May 18, 2019
  61. Chemistry

    you have 0.05246 moles of P4 the 11.54g of oxide contain 5.04 g of oxygen, which is 0.315 moles of O 0.315/0.05246 = 6 That means you get 6 moles of O for every mole of P4 See what you can do with that.

    posted on May 18, 2019
  62. Physics 20

    I expect that you are to consider only the rock's horizontal speed. In that case, just recall that time = distance/speed. So, if the rock's speed was x m/s, we need the total round-trip time of rock and sound to be 4.5 s. That means we have to solve 50/x +

    posted on May 18, 2019
  63. Physics 20

    those are not vector values, or even x-y coordinates. I guess you can do vectors on the number line, but that's not usually how it's done. google is your friend, and can provide many examples. as I'm sure your class text can ...

    posted on May 18, 2019
  64. Pharmacy calculations

    just get out your conversion factors for changing oz and tsp to mL I assume you mean fl oz, since that is a volume unit. do the conversions, and add them up.

    posted on May 18, 2019
  65. Math

    you cannot integrate sin(x^2) using elementary functions. Some numeric method is needed, or one of the special functions defined as integrals. In this case, the Fresnel Integral.

    posted on May 18, 2019
  66. Math

    Draw the triangle PAB ∡B = 38° ∡A = 33° side p = 3.9 So, ∡P = 109° Using the law of sines, b/sin38° = 3.9/sin109° b = 2.54 km

    posted on May 18, 2019
  67. Maths

    dx/dt = 5 dy/dt = 3x^2 dx/dt Now, the gradient is g(x) = dy/dx = 3x^2 the rate of change of the gradient is dg/dt = 6x dx/dt = 6*5 = 30 If the answer is supposed to be 3, then I must have misread the problem. O course, there's always the chance that you

    posted on May 18, 2019
  68. Maths

    Draw the triangle. It has sides 5-12-13 so, csc theta = 13/5

    posted on May 18, 2019
  69. Calculus

    #1 ok #2 ok #3 nope. 11/23 use implicit differentiation #4 ok #5 f = -e^x+x f' = 1-e^x f'=0 at x = 0 f(0) = -1 #6 ok #7 Nope The area is triangle+rectangle+triangle-semicircle 3 + 3 + 3/2 - 2pi = 15/2 - 2pi #8 ok #9 maybe. If that leading "-" sign belongs

    posted on May 18, 2019
  70. math

    what, no calculator?

    posted on May 18, 2019
  71. Math

    well, right and up are in a positive direction (add to x,y) left and down are in a negative direction (subtract from to x,y) NOW what would you say?

    posted on May 17, 2019
  72. physics

    just use your basic equations of motion s = vt + 1/2 at^2 If the cop starts moving just as the car zips by, then we have the distance traveled after t seconds as car: 25t cop: 1/2 * 3 t^2 time elapsed till the cop catches up: 25t = 3/2 t^2 Now you can

    posted on May 17, 2019
  73. Math

    add 6 to both sides and you get y > 18 (or y≥18 if that's what you want) In any case, the solution set is all numbers greater than (or equal to?) 18

    posted on May 17, 2019
  74. Geometry

    I'm assuming that L is the slant height, so your formula for total area is correct pi R^2 + pi RL I have no idea what the "next step" is supposed to be, since you already have the total area. Is 4 the radius of some other cone, with slant height 10? If so,

    posted on May 17, 2019
  75. Geography

    360°/24hr = 15°/hr so they are one time zone away. now you must decide whether they are ahead or behind ...

    posted on May 17, 2019
  76. Social studies

    hmmm. you seen to have forgotten to include your choices...

    posted on May 17, 2019
  77. Math

    since every number on such a cube is less than or equal to six, there's nothing else you can roll. P(

    posted on May 17, 2019
  78. math

    no, it is not

    posted on May 17, 2019
  79. Math, algebra 1

    if the flare burns longer than 3 seconds, it will still be burning on the way down.

    posted on May 17, 2019
  80. physics

    ice-steam is 100°C 19 is 6/11 of the way from 13 to 24, so the temperature is 6/11 * 100 = 54.54°C

    posted on May 17, 2019
  81. Physics

    Jack can run 780m in 60 s Zeke can run 435m in 60s 435+350 = 785 so, what do you think?

    posted on May 17, 2019
  82. math

    well, it's (x+2)(x-3) / (x+2)(x) so, what do you think?

    posted on May 17, 2019
  83. math

    so, how did you get 367? Maybe an obvious tweak will present itself. And what is that "x" doing in there? Is that where it belongs?

    posted on May 17, 2019
  84. math

    that would of course be 5 * 2/3 = _____ jars now round down to a whole number, if that's what you want.

    posted on May 17, 2019
  85. Calculus

    If you mean f(x) = ∫[x,1] √(1+t^2) dt then f'(x) = -√(1+x^2) so, f'(1) = -√2 This is just the chain rule in reverse. If F(t) = ∫f(t) dt then F'(t) = f(t) So, if u,v are functions of x, then ∫[u,v] f(t) dt = F(t) [u,v] = F(v)-F(u) Now take

    posted on May 17, 2019
  86. Chemistry

    well, the ratio is 120:6 = 20:1 = 200:10

    posted on May 16, 2019
  87. Calculus help

    #2 f(x) has a max where f'=0 and f" < 0 f = (x+2)(x+3)^2 f' = (1)(x+3)^2 + (x+2) * 2(x+3)*1 (product and chain rules) = (x+3)(x+3+2x+4) = 2(x+3)(x+2) = 2(x^2+5x+6) f" = 2(2x+5) So. f'=0 at x = -3, -2 f"(-3) < 0 f"(-2) > 0 so, the max is at x = -3 #3 f(x) =

    posted on May 16, 2019
  88. Algebra

    google is your friend. Lots of explanations and videos available. Or, maybe your class text?

    posted on May 16, 2019
  89. Math

    I suspect a typo, and the last line should be 2 1 and geez, bruh, try out the rules to see which one fits, if you can't figure it out. duh!

    posted on May 16, 2019
  90. Calculus help

    huh? just plug and chug If u and v are functions of x, then if y = uv y' = u'v + uv' you gotta problem with that, pal?

    posted on May 16, 2019
  91. Chemistry

    240/7200 = 1:30

    posted on May 16, 2019
  92. math

    hmmm. I'd say check the corresponding sides and angles ...

    posted on May 16, 2019
  93. math

    No. 5P3 = 5*4*3 = 60

    posted on May 16, 2019
  94. geometry

    use the law of cosines to get, say angle R. 17^2 = 10^2 + 21^2 - 2*10*21 cosR cosR = 3/5 Now find the altitude h from P using h/10 = sinR = 4/5 h = 8

    posted on May 16, 2019
  95. math

    correct

    posted on May 16, 2019
  96. algerbra

    5^-1 = 1/5 so, -(5)^-2 = -1/5 except for zero, anything to the zero power is 1. Think about it. x^3/x^3 = x^(3-3) = x^0 whatever number you choose, raising it (or any power of it) to the zero power just gives 1. Negative powers switch numbers from the top

    posted on May 16, 2019
  97. Algebra

    y+x=3 y-2x=18 subtract the bottom from the top and you have 3x = -15 x = -5 so, y = 8

    posted on May 16, 2019
  98. algebra

    √45 = √(9*5) = √9√5 = 3√5 to factor out the 3, you need to factor out √9. You just factored out √3. √45 = √3√15 √180x^2 = √(36*5x^2) = 6x√5 √250h^4 k^5 = √(25*10h^4 k^4*k) = 5h^2k^2√(10k) Interesting that you got this one

    posted on May 16, 2019
  99. physics

    for each coordinate (x,y,z) find the weighted average of all the masses times their distances. For example, Mx = (5*1 + 2*1 + 3*1)/3 = 10/3 do My and Mz similarly

    posted on May 16, 2019
  100. Chemistry

    how many moles NaHCO3 in 16.8 g? each mole occupies 22.4 L, right?

    posted on May 16, 2019