# oobleck

Popular questions and responses by oobleck
1. ## Calculus - Integration

I ran across this one the other day. See what you can make of it. Find the integral of ecosxsinx - (sinx+cosx)esinx+cosx ----------------------------------------- esin2x-2esinx+1

1. ## math

(9.71-9.8)/9.8 = -0.00918 * 100% = -0.918%

posted on June 2, 2020
2. ## Physics

consider the height of the ball. y = v sinθ t - 16.1t^2 what is v? no idea, but we do know that with a constant horizontal speed of v cosθ, it flew 196 feet. so, t = 196/(v cosθ) Plug that in, and you just have to solve y = 196 tan30.3° - 16.1t^2 =

posted on June 2, 2020
3. ## Chemistry

PV/T is constant, so you want 4.81V/(91.60+273.15) = 1*(21.5*22.4)/273.15

posted on June 2, 2020
4. ## precal

it is discontinuous, because the denominator is zero at x = -2, -5

posted on June 2, 2020
5. ## Calculus

Just treat y as a constant. Then apply the quotient rule

posted on June 2, 2020
6. ## mathemathics

kinda missing some information, eh? If you know how to find the volume and area of a prism, though, it should not be too hard.

posted on June 2, 2020
7. ## MATH

well, 18 is the minimum 42 is the maximum the sum of six odd numbers must be even So only 26 is left.

posted on June 2, 2020
8. ## math

nope. 2 for Jeff 3 for Maria so, Jeff got 2/5 of the shells, not 2/3. This illustrates the difference between probability (2/5) and odds (2:3)

posted on June 2, 2020
9. ## math

one which is just a multiple of another 2/3 = 4/6 = 10/15 etc. They are all equivalent.

posted on June 2, 2020
10. ## Mathematics

the midpoiint of the diameter (2,3) is the center of the circle. So the equation is (x-2)^2 + (y-3)^2 = r^2 r is half the length of the diameter, so ...

posted on June 2, 2020
11. ## history

whining won't get you help any faster. While you're waiting, have you done some googling?

posted on June 2, 2020
12. ## Chemistry

10 days * 2doses/day * 10mL/dose * 50mg/mL = 10*10*2*50 mg

posted on June 2, 2020
13. ## mathematics

#1 see your previous post #2: sin(cos^-1(1-x)) Let cosA = 1-x Draw a triangle with angle A such that the adjacent leg is (1-x) and the hypotenuse is 1. Then the opposite leg is √(1 - (1-x)^2) = √(2x-x^2) Now you can tell sinA. #3. Use the law of sines.

posted on June 2, 2020
14. ## Mathematics

r/b = 2/3, so r = 2/3 b (r-3)/b = 3/5 5(r-3) = 3b 5(2/3 b - 3) = 3b now finish solving for b

posted on June 2, 2020
15. ## mathematics

sqrt(6-3x)-2=0 sqrt(6-3x) = 2 6-3x = 4 so, what do you think?

posted on June 2, 2020
16. ## Mathematics

hav B = 0.2351

posted on June 2, 2020
17. ## Mathematics

= t(8-t)

posted on June 1, 2020
18. ## math

75% and 25% are multiples of 1/4 So how many multiples of 4 are there in 1000?

posted on June 1, 2020
19. ## math

.75 * 100 = 75

posted on June 1, 2020
20. ## Mathematics

You have two pairs of triangles, right? You have the base and height, so just do the math.

posted on June 1, 2020
21. ## Math

well, it is clear that you keep multiplying by 4, right? That only leaves one choice

posted on June 1, 2020
22. ## Precalculus

y = (t-3)^2 - 4 = t^2-6t+5

posted on June 1, 2020
23. ## Physics

did it burst into flame?

posted on June 1, 2020
24. ## maths

since f(x) is defined for x=2, it is just 2^2+1 = 5 for x>2, the limit would be (2-3)^2 = 1 Since the limits are not the same, you cannot have both f(x)={x²+1 if x≤2 {(x-3)² if x≥2 it must be either f(x)={x²+1 if x≤2 {(x-3)² if x>2 or f(x)={x²+1

posted on June 1, 2020
25. ## mathematics

you want 0.095 to be 9.5x10^___ how many places to the right did you shift the decimal point?

posted on June 1, 2020
26. ## Maths

(2W)(2L) = 4WL 4 times the area, 4 times the time.

posted on June 1, 2020
27. ## math

probably only a hundred books or so, and 100/4 = 25 So, a reasonable breakdown would be 3/4 = 75/100 non-fiction

posted on June 1, 2020
28. ## Mathematics

as written, it is not true. I think you meant (1-sin2x)/cos2x = (1 - 2sinx cosx)/(cos^2x - sin^2x) = (cos^2x - 2sinx cosx + sin^2x)/(cos^2x - sin^2x) = (cosx-sinx)^2 / ((cosx-sinx)(cosx+sinx)) = (cosx-sinx)/(cosx+sinx) = (1-tanx)/(1+tanx) = tan(π/4 - x)

posted on June 1, 2020
29. ## Precalculus

it hits the ground when the height is zero, right? So just solve 6 + 95 sin25° t - 16t^2 = 0

posted on June 1, 2020
30. ## Precalculus

Assuming down the alley toward the pins is the +y direction, then (x,y) = 7*1.5 * (cos87,sin87)

posted on June 1, 2020
31. ## precalculus

note that x^2+y^2 = 9 now review how angles are graphed in polar coordinates.

posted on June 1, 2020
32. ## Math

find the limit of (f(x+h)-f(x))/h = [((x+h)^2 - 3(x+h) + 5) - (x^2-3x+5)]/h You should wind up with 2x-3

posted on June 1, 2020
33. ## math

compare 7:5 to 40:30 or, 70:50 to 4:3 the size of the ratio says nothing about the total quantities

posted on June 1, 2020
34. ## math

alternate signs as in -,-,+,+,-,-,+,+,... and just keep multiplying by 4 a_n = (-1)^(1+[(n-1)/2] * 6 * 4^(n-1) where [x] is the greatest integer (floor) function

posted on June 1, 2020
35. ## math

r:b = 5:6 b:g = 3:4 = 6:8 r:b:g = 5:6:8 = 10:12:16 and so on there are many ways to do this, just multiplying those three numbers by any desired value

posted on June 1, 2020
36. ## Mathematics

K/4650 = 3/5 now just solve for K

posted on June 1, 2020
37. ## chemistry

M = mol/L so you are correct.

posted on May 31, 2020
38. ## Science

compare 0.12 * 150 with 0.15 * 120 And a question cannot be true or false -- it is a question.

posted on May 31, 2020
39. ## math

oops. no math is required. I figured how many slices were eaten... There were 12 slices, and 5 are left. So, 5 bags needed.

posted on May 31, 2020
40. ## math

12/12 - 5/12 = ___/12

posted on May 31, 2020
41. ## math

Matt's score ... m 23 less than m ... m-23 is ... = and so on.

posted on May 31, 2020
42. ## math

a) your answer is correct, but you have an extra paren in lin e 3. (1^2 - (3(1)+5)/(1-2) should be (1^2 - 3(1) + 5)/(1-2) b) is also correct

posted on May 31, 2020
43. ## Algebra

(a^2a^4)÷a^−3 = (a^2a^4)*a^3 = a^6*a^3 = a^9 a/(a^2a^3)^4 = a/(a^5)^4 = a/a^20 = a^-19 a^9÷a^-19 = a^9 * a^19 = a^28

posted on May 31, 2020
44. ## Mathematics

If you don't have a protractor, it is easy to construct the 105° angle, since 105=90+15 So just make a 90° angle make a 60° angle and bisect it twice to get the 15° angle Then add them together.

posted on May 31, 2020
45. ## Math

Hard to parse your table. Are the first six values x and the last 5 y? Why are there not 12 values? As a first guess, I'd say the next x is -4, since the differences go -12, -6, -12, -6 The y differences go -12, 4, -12, 4 The extra ? stumps me.

posted on May 31, 2020
46. ## Mathematics

(a) less improvement as just a number of points, or as a percentage? points: 30 > 18 percent: 18/30 > 1/2 30.60 = 1/2 (b) E+M-(E&M) = U-7 38+M-9 = 63 Now you can answer the questions.

posted on May 30, 2020
47. ## mathematics

well, S720E is just S so what is 20° less than S? S = 180°, so 180-20 = 160°

posted on May 30, 2020
48. ## math

c+a = 292 1.50c + 4.00a = 838.00 Now just solve for c and a.

posted on May 30, 2020
49. ## mathematics

p= 1.8cm If you meant P, then use the law of cosines p^2 = q^2 + r^2 - 2qr cosP

posted on May 30, 2020
50. ## mathematics

recall the law of sines sinA/a = sinB/b Once you have A, then C = 180-(A+B)

posted on May 30, 2020
51. ## mathematics

posted on May 30, 2020
52. ## Physics

I think I'd go with E. google turned up the following explanation: Note that as a group, the unsaturated fatty acids have lower melting points than the saturated fatty acids. The reason for this phenomenon can be found by a careful consideration of

posted on May 30, 2020
53. ## Algebra

a_1 = 1/2 a_2 = 3/4 a_3 = 21/16 Now, since x^2+x > x^2 and a_n > 1 for n > 2 and (x^2+x/x) = x + 1 a_4/a_3 > a_3+1 = 37/16 > 3/2 The a_n are always increasing, and since a_3 >3/2, a_n > 5/2 for all n > 3 And, a_(n+1)/a_n = a(n) + 1 > 3/2 So, even though

posted on May 30, 2020
54. ## Mathematics

#1) 181+142+117-(75+60+54)+x = 200 I suspect a typo.

posted on May 30, 2020
55. ## Math

800 cos39° you decide whether that's east or west. It won't be both...

posted on May 30, 2020
56. ## Math

depends on the size of the walls ... double the area and divide by 100 to find the quarts needed (round up)

posted on May 30, 2020
57. ## algebra

a+b = 2 a-b = -4 add the two lines and you get 2a = -2 and the rest is easy.

posted on May 30, 2020
58. ## math

again?

posted on May 30, 2020
59. ## Algebra

In vertex form, f(x) = a(x-h)+k where the vertex is at (h,k) f(x)=2/5x^2-4x+14 = 2/5 (x^2 - 10x) + 14 = 2/5 (x^2 - 10x + 25) + 14 - 2/5 * 25 = 2/5 (x-5)^2 + 4 So the vertex is at (5,4) as above

posted on May 29, 2020
60. ## Algebra

Just as a shortcut, for nPk, start at n and count down for k factors. For example, 9P3 = 9*8*7 for combinations, do the same, but divide by k factors counting up 12C4 = (12*11*10*9) / (1*2*3*4) Note that this makes it clear why you never have to go more

posted on May 29, 2020
61. ## physics

v = fλ = λ/t so you are correct

posted on May 29, 2020
62. ## Algebra

#1: 6/20 * 5/19 * 4/18 = 1/57 #2 chance of (brown,orange,orange) = 5/20 * 2/19 * 1/18 but the brown can happen in any of three places, so the final probability is 3(5/20 * 2/19 * 1/18) = 1/228 Too bad you couldn't be bothered to show your work - just

posted on May 29, 2020
63. ## Math

well, that would be 40% of 26, right? 0.40 * 26 = ____

posted on May 29, 2020
64. ## Math

looks good to me.

posted on May 29, 2020
65. ## Math

rats - y = -√33

posted on May 29, 2020
66. ## Math

in QIII, x

posted on May 29, 2020
67. ## Math

your calculations are correct, but that is not C

posted on May 29, 2020
68. ## math

3 points for every field goal points depends on goals, right?

posted on May 29, 2020
69. ## math

no diagram

posted on May 29, 2020
70. ## math

divide both sides by nR

posted on May 29, 2020
71. ## math

well, how many weeks is that? multiply that by 1/3 * \$25

posted on May 29, 2020
72. ## Algebra

since (a+b)^2 = a^2 + 2ab + b^2, we have (2√5+3√7)^2 = (2√5)^2 + 2(2√5)(3√7) + (3√7)^2 = 4*5 + 12√5√7 + 9*7 = ...

posted on May 29, 2020
73. ## Calculus/Vectors

recall that T = rFsinθ so plug in your numbers

posted on May 29, 2020
74. ## mathematics

They all say the same thing (D only if you already know A or B or C) I like C simpler than fractions, and the raw numbers in D really don't convey any information.

posted on May 29, 2020
75. ## math

v = dy/dx = dy/dt / dx/dt = (e^t-2cost)/(1/t + 3t^2) a = dv/dx = dv/dt / dx/dt = [(e^t+2sint)(1/t + 3t^2) - (6t - 1/2)(e^t-2cost)]/(1/t + 3t^2)^3 This is just a stupid exercise -- needlessly complicated.

posted on May 29, 2020
76. ## Algebra

again? 4√6/√30 * √30/√30 = 4√180/30 = 4*6√5/30 = 4√5/5 or 4√6/√30 = 4√6 / √5√6 = 4/√5 = 4√5/5

posted on May 29, 2020
77. ## Physics

net force is the sum of all the forces acting on the object. Then, of course, F = ma if there is a nonzero net force, the object will undergo an acceleration.

posted on May 29, 2020
78. ## Physical Science

assuming the pressure remains the same, V1/T1 = V2/T2 not sure how going from 1.2 cm^3 to 200 cm^3 is a decrease, though ...

posted on May 29, 2020
79. ## Maths

red: P(male) = 1/3 blue: P(female) = 1/3 so, 1/9 that he will get both the needed gp's.

posted on May 29, 2020
80. ## math

HCF(64,124) = HCF(4*16,4*31) = 4 LCM(64,124) = 64*124 / HCF(64,124)

posted on May 29, 2020
81. ## pre-calculus

use the law of sines: b/sinB = a/sinA

posted on May 29, 2020
82. ## mathematics

(h-1.7)/25 = sin30°

posted on May 29, 2020
83. ## Trig

tan>0 and cos

posted on May 28, 2020
84. ## Algebra

See if you can show that a_(n+1) > 3/2 a_n Having that, now you know that 1/(a(n+1)+1) < 1/a(n+1) < 2/3 1/a_n That means that each term of the sum is less than the corresponding term in the geometric sequence a = 2/3 r = 2/3 The infinite sum of that is

posted on May 28, 2020
85. ## science

what kind of magazine?

posted on May 28, 2020
86. ## algebra

red = a white = a/2 total = a + a/2 = 3/2 a

posted on May 28, 2020
87. ## Calculus

a×b ⊥ a and b c = {3, 5, -4}×{-3, 1, -5} = {-21,27,18} and of course, -c is also ⊥ to a and b

posted on May 28, 2020
88. ## Calculus

just plugging the various values for n, I get sum(1..∞) = ln 2 = 0.69314718 so we want the sum to lie between 0.69304 and 0.69324 sum(1..9) = 0.7456 sum(1..99) = 0.6981 sum(1..999) = 0.6936 sum(1..9999) = 0.693197

posted on May 28, 2020
89. ## Calculus

so, did you use the table? It will probably provide a reduction formula, such as ∫x^n e^ax dx = 1/a x^n e^ax - n/a ∫ x^(n-1) e^ax dx this is achieved using integration by parts. So, going through that three times gives you (1/9 x^3 - 1/27 x^2 + 2/243 x

posted on May 28, 2020
90. ## math

P: (x,y) → (x,b-(y-b)) = (x,2b-y) Q: (x,y) → (x,2a-y) P∘Q: (x,y) → (x,2a-(2b-y)) = (x,2a-2b+y)

posted on May 28, 2020
91. ## Algebra

for any x, x + 6x = 7x You just happen to have x = sqrt5

posted on May 28, 2020
92. ## Algebra

I assume you mean y = 1/2 x - 3 So, just pick two values for x, say, 0 and 1, and figure what y is for each.

posted on May 28, 2020
93. ## Maths

let P = (m,15/8 m) Q = (n,3/10 n) Then since PR=QR, (8-m)^2 + (6 - 15/8 m)^2 = (8-n)^2 + (6 - 3/10 n)^2 and, since the slope of PR = slope of QR, (15/8 m - 6)/(m-8) = (3/10 n - 6)/(n-8) Solving for m and n, we have m = 32/7, n = 80/7 Plugging that into the

posted on May 28, 2020
94. ## Math

yes. after removing the parentheses, that would be the same as adding -7x+12-3x^2

posted on May 28, 2020
95. ## geometry

posted on May 28, 2020
96. ## math

1030/95 = ____

posted on May 28, 2020
97. ## Algebra

just subtract 4 from each element of the domain

posted on May 27, 2020
98. ## mathematics

I'd guess non-negative integers (up to some reasonable maximum)

posted on May 27, 2020