Wednesday
November 26, 2014

Posts by STEVE


Total # Posts: 27,019

celebrating Diversity
excuse me? I see no mention of sex anywhere in the statement! It is clearly stereotyping.
October 23, 2014

Algebra
correct. You can easily check your results for yourself at wolframalpha.com
October 23, 2014

physics
what is a "4N point" ? and your cosine hints are mangled.
October 23, 2014

Algebra
What is the 9th term of the arithmetic sequence defined by the rule below? A(n)=-14+(n-1) (2)
October 23, 2014

algebra
note the slope from point to point: (2150-2200)/(20-15) = -50/5 = -10 (2050-2150)/(30-20) = -100/10 = -10 (1750-2050)/(60-30) = -300/30 = -10 So, it looks like F = -10T But, F(15) = 2200, not -150 SO, making that adjustment, we have F = 2350 - 10T
October 23, 2014

Algebra
Sound travels at 343 meters per second. How far does it travel in 8 seconds? My answer is 2,744 meters.
October 23, 2014

Algebra
Thank you -- I'm a gandparent trying to check my grandson's homework
October 23, 2014

Algebra
Is the following relation a function? ((0.3, 0.6). (0.4,0.8), (0.3,0.7), (0.5,0.5))
October 23, 2014

Math (Functions - Word Problem)
what's the trouble? Just sub in the values. Just watch that you change which definition of d(t) you use for the portions of the domain. year t d(t) 2000 0 10.6+0+699 = 699 2001 1 ... ... 2005 5 15.5*5+637 = 7145 2006 6 ... ...
October 23, 2014

trigonometry
If the tower has height h and is at a distance x, then h/x = tan 60° (h-6th)/x = tan 45° Eliminating h, we have x/tan 60° = x tan 45° + 6th x(1-1/√3) = 6th x = 6th/(1-1/√3) whatever 6th is supposed to mean.
October 23, 2014

Maths Question
since y'=0 at x=1,2,3,4,5 the max/min can occur there. But, y' has roots of even multiplicity at x=2 and 4, so those will be inflection points. So, extrema will occur at x=1,3,5 Why? The slope has to change sign at the extrema. If y' has roots of even multiplicity...
October 23, 2014

math
Well, since 7777-4444 = 3333 I've no idea. 7654-4567 = 3087 hmmm. still 90 off So, he must have done 7564-4567 = 2997 or 7654-4657 = 2997 So, he must have transposed two digits as shown above. That, as well as assuming that he could not repeat digits in the numbers.
October 23, 2014

Math
just plug in numbers for the letters a and s, and evaluate the expression.
October 23, 2014

algebra
How about x-3 + x + 2x+1 = 26
October 22, 2014

math
how long is the shelf? I don't feel like searching through all your posts to collect missing data.
October 22, 2014

math
how long is the shelf? You sure you want the thickness of a DVD case in feet?
October 22, 2014

geometry
v = 3.14 * 3^2 * 12
October 22, 2014

pre calc
Use your favorite quadratic regression calculator. I got P = 672.619t^2 - 7863.0952t + 64071.4286 but it's not a very good fit.
October 22, 2014

algebra
Look at the data, using just the changes (1600-760)af/(60-40)°F = 42 af/°F (2020-1600)af/(70-60)°F = 42 af/°F (2650-2020)af/(85-15)°F = 42 af/°F I guess that tells the story, eh?
October 22, 2014

math
3/4 + 1/9 find each sum
October 22, 2014

college algebra
C(t) = 14500 + 6.75t
October 22, 2014

Algebra Slope Intercept Form
or, just y = 1/5 x
October 22, 2014

Algebra Slope Intercept Form
correct
October 22, 2014

Calc
f(0) = 1+0 = 1 f(2pi) = 1+0 = 1 f'(x) = -sinx + 2sinx cosx = sinx(2cosx-1) So, f'=0 at x=0,pi,2pi and pi/3,5pi/3 f(pi/3) = 1/2 + 3/4 = 5/4 f(pi) = -1+0 = -1 f(5pi/3) = 1/2 + 3/4 = 5/4 Looks like the min is -1 and the max is 5/4 See http://www.wolframalpha.com/input/?i=...
October 22, 2014

arithmetic
If you want to find 8-0, recall that 8-8 = 0 so, 8-0 = 8 9-3? 9-6=3, so 9-3=6 Just google subtraction related facts, and study up some.
October 22, 2014

Algebra
the minimum point on a parabola is its vertex. So, find the vertex. For y = ax^2+bx+c, the vertex is at x = -b/2a. In this case, that is x = -12/2 = -6 AT x=-6, y = -31 This can be seen by rearranging the equation into the vertex form. x^2+12x+5 = (x^2+12x+36) + 5 - 36 = (x+6...
October 22, 2014

math expressions
b = 2g+5 b+g = 89 so, 2g+5+g = 89 Your question is a bit garbled, but I expect you can devise an answer using the above equations.
October 22, 2014

Science Density
well, the volume of water displaces is 150*90*8 cm^3 If the person is floating, her mass is the same as the water displaced. If the person is submerged completely, her volume is the same as that of the water. So, if you know the person's density, that can be used. If ...
October 22, 2014

Not So Fast
Not so fast. We have the hypotenuse = 17 x^2 + 15^2 = 17^2 x = 8 So, B is correct
October 22, 2014

Math
f = x^(1/6)−x^(−5/6) f' = (1/6)x^(-5/6) + (5/6)x^(-11/6) = (1/6)x^(-11/6)(x+5) so, where is f' = 0?
October 22, 2014

Math
-2x^2-8x+17 = -2(x^2+4x) + 17 = -2(x^2+4x+4) + 17 + 2*4 = -2(x+2)^2 + 25 Now just read off the vertex.
October 22, 2014

Trig
If you mean cot(θ-π/2) then that's easy just as sinθ = cos(π/2-θ), tanθ = cot(π/2-θ) and, since cot(-θ) = -cotθ, cot(θ-π/2) = -cot(π/2-θ) = -tanθ Oh, well, if you must, show that cot(θ-π/2...
October 22, 2014

math
whatever do you mean by "next level"?
October 22, 2014

Algebra 1
I think that the level of problems presented indicates the intent is -2/5 x - 9 < 9/10 -4x - 90 < 9 -4x < 99 x > -99/4
October 22, 2014

Algebra
since time = distance/speed, you have d/(150-30) + d/(150+30) = 3 Now just solve for d
October 22, 2014

maths
the game is 120 minutes long. He misses the goal if he arrives during the last 100 minutes, so p = 100/120
October 22, 2014

Algebra
3*120 <= 135+145+x <= 3*130 360 <= x+280 <= 390 80 <= x <= 110
October 22, 2014

algebra
If the short side is x, then x + x+6 + 2x-2 = 24 Now, just find x and figure the sides.
October 22, 2014

math
30 incorrect means 30(1 1/2)=45 correct. So, how many altogether?
October 22, 2014

maths
14000(1 + .12*2)
October 22, 2014

Trigonometry
356
October 22, 2014

physics
no idea - what is it filled with?
October 22, 2014

statistics
12500 rec * 30min/rec * 1hr/60min * 1emp/2080hr = (12500*30)/(60*2080) = 3.0 emp
October 22, 2014

math
pure gold is 24K, so 22K gold is 22/24 = .917 18K gold is 18/24 = .750 14K gold is 14/24 = .583 The problem clearly has a typo when it mentions 18K gold. A 22K statue the same weight as a 14K statue contains more gold. The difference is (22-14)/24 * 73.5 or, given all the ...
October 22, 2014

math
15*852 = 12,780 assuming all those who bought tickets watched the show ...
October 22, 2014

Math
well, check your math. Starting with $60, that means 20 on books, leaving 40 16 on games, leaving 24 6 on DVD, leaving 18 3 on candy, leaving 15 We have a winner! Your final step in concluding that if 1/4 of the money is $15 then the whole was $60 is correct. But your original...
October 22, 2014

physics
s = vt + 1/2 at^2 Now just plug in v=247, a=28, t=8.7
October 22, 2014

math
if the model has diameter 31.9 cm, its area is π*31.9^2 = 3196.92 cm^2 So, divide that by 2 and then by 10 to get the number of jars
October 22, 2014

Math 222
in the first, each term contains a power of a and a power of b. You need to find the highest power of a and b that divides each term. That would look like a^2 a^2 b + a^2 b^2 b Now factor out the a^2 b, leaving the indicated solution. Recall that a^m a^n = a^(m+n) Review the ...
October 22, 2014

physics
constant speed means zero acceleration!
October 21, 2014

Math 222
I assume you want to factor the expressions? a^4b + a^2b^3 = a^2b(a^2+b^2) z^2 + 18z + 45 = (z+3)(z+15)
October 21, 2014

calculus
arcsin(ix) = i arcsinh(x)
October 21, 2014

math
600rev / (44 8/9 rev/min) = 13 37/101 min
October 21, 2014

Physics
(83.59)(1.44/9.81)
October 21, 2014

math
come on 1/2 = .5000 2/3 = .6666 So, anything in between, such as .58345... .66217...
October 21, 2014

math
24/18 = 4/3 6.12/4.5 = 1.36 That's pretty close to the same ratio, so just scale up by 18/4.5 = 4 Just multiply each dimension by 4. That will produce a size of 18 by 24.48
October 21, 2014

Math
the sides are 22,x,2x-2, so we have 2x-2-x < 22 < 2x-2+x x < 24 < 3x So, it looks like 8 < x < 24
October 21, 2014

Trigonometry
what you have is cosθ + 1 = 2cos^2θ - 1 2cos^2θ - cosθ - 2 = 0 so, solve that quadratic for cosθ and pick the choice.
October 21, 2014

Algebra
d = 2q 5n+10d+25q = 440 There will probably be no single solution, since you only have two equations.
October 21, 2014

Math HELP!
A. No - 3.2 is real, not integer B. true C. No - 2/3 is not a perfect square D. No - NO integer is irrational You were just guessing, I presume.
October 21, 2014

math
there is only one answer. I guess they want you to attack it in three different ways. Seems kind of pointless to me.
October 21, 2014

maths
just set up the equations: a+2d + a+6d = 38 a+8d = 37 Now just solve for a and d.
October 21, 2014

Algebra
the second car is going 15 mph faster than the first when the 2nd cars starts out, the 1st car has gone 50 miles already. So, how long does it take to make up 50 miles, going a relative speed of 15 mi/hr?
October 21, 2014

Math
just set up two expressions for the costs, and set them equal. For m minutes, you want .08m = 6.00 + .02m Now just find m which makes the two values equal.
October 21, 2014

Algebra: Answer Check
looks good to me.
October 21, 2014

Calculus
It appears you are trying to approximate ∛7.9 So, if y = ∛x, then dy = 1/(3∛(x^2)) dx at x=8, y=2, so if dx = -0.1, dy = 1/(3∛64) (-0.1) = -1/240 = -.0042 So, ∛7.9 ≈ 1.9958 check: ∛7.9 is 1.9916 The estimate is expected to be a bit ...
October 21, 2014

Homework (Science)
it hits the ground when the height is zero. So, just solve 32.5t - 4.9t^2 = 0
October 21, 2014

Math
consecutive integers differ by 1. Pick any two adjacent elements of the list below: 1,2,3,4,5,6,7,8,9,... For example, 6 and 7. Those are consecutive integers. SO, you have two numbers, a=n and b=n+1 n/2 + (n+1)/2 = (n + n+1)/2 = (2n+1)/2 = n + 1/2 Since n is positive, n >...
October 21, 2014

Algebra
Change the 60 to -60 and then the underlined portion will be correct. Changing the underlined 20 to -20 would also work, but then you have nonsense: -3 < N < -20 which cannot be true for any value of N If you know about tags, you can use the u and /u tags to enclose ...
October 21, 2014

math
229 is clearly bogus! That is below the mean! I get 1.75 std above the mean for the top 4% better check that figure again.
October 20, 2014

Pre-Calc
(T-A)/(To-A) = e^-kt We have (60-93)/(45-93) = e^(-23k) e^(-23k) = .6875 k = .0163 So, now we want to find when T=77 e^(-.0163t) = (77-93)/(45-93) = 0.333 t = 67.4 minutes Nice model, but I'm sure that in real life, after more than an hour, that pop is very nearly 93 degrees!
October 20, 2014

Math
10 ∑(2k+4) = 144 k=2 You want to find the upper summation limit for the other values. So, what is n ∑(2k+4) = n(n+5) k=1 Note that Sum(2,10) = sum(1,10) - sum(1,1) = 150-6 = 144 Sum(4,12) = Sum(1,12)-Sum(1,3) = 204-24 = 180
October 20, 2014

Math 11
(A) 19 cot25° + 26.8 cot47° (B) 19 csc25° + 26.8 csc47° Draw a diagram and review your basic trig function definitions
October 20, 2014

math
how many digits? You could have anything from 2 to 11111111...2 where there are 98 1's
October 20, 2014

calc
so, how many intervals? Give us your idea of a table of values for the approximation.
October 20, 2014

calculus
f'(x) = 2x-5 f'(1) = -3 So, the line with slope -3 through (1,-2) is y+2 = -3(x-1) Not sure what your four-step process is.
October 20, 2014

Math
18 boys play something. If b play both, then 13+15-b = 18
October 20, 2014

Math
You want x such that x(1.029)^(9/12) = 3262.50 x = 3193.29
October 20, 2014

Math
If there were n questions, then .80n = 22 n = 22/0.8 = ? Oddly, the result is not an integer. Typo? Rounded score?
October 20, 2014

calculus
f(t) = 1/3 (9t^2 + t^5) f'(t) = 1/3 (18t + 5t^4) = 1/3 t(18+5t^4) f'=0 where x=0 or ±∜3.6
October 20, 2014

MATHS
Assuming a typo, I have 6m^2 + 31m + 33 = 0 (2m+3)(3m+11) = 0
October 20, 2014

Calculus
since e^4x is always positive, and f'(x) = 2x e^4x (2x+1) f'=0 when x=0 or x = -1/2 f' < 0 where x < -1/2 f' > 0 where -1/2 < x < 0 f' > 0 where x > 0 This is clearly shown at http://www.wolframalpha.com/input/?i=+x^2+e^%284x%29+for+-1...
October 20, 2014

Calculus
f(x) = 2x/(6x+12) f(1) = 1/9 f(4) = 2/9 (f(4)-f(1))/(4-1) = 1/27 The MVT says that there is c in [1,4] such that f'(c) = 1/135 f'(x) = 2/3 (x+2)^-2 So, 2/3 (c+2)^-2 = 1/27 c = 2.24 which is inside [1,4]
October 20, 2014

Math
just use the double-angle formula: cos2A = 2cos^2 A - 1
October 20, 2014

Math
what does "2x6x" mean
October 20, 2014

Algebra
hmmm taht would be when 110-30t = 40 so, just solve for t. Also, lose the "m".
October 19, 2014

Algebra
Start from 110 feet away, a person on a bicycle rides toward a checkpoint and then passes it. The rider is traveling at a constant of 30m feet per second. The distance between the bicycle and the checkpoint is given by the equation d=(110-30t). At what times is the bike 40 ...
October 19, 2014

physics
Treat the i and j components separately Also, noting that F = ma, (30.7-12.0+x) = -8.00*2.44 (17.0+8.00+y) = 6.00*2.44 That will give you the third force, xi+yj
October 19, 2014

Math/Science
Unless you tell us something about the velocity of the resulting 3-bullet lump, there's no way to tell anything about its mass. Also, are the three gun muzzles arranged in a circle parallel to the plane of the target?
October 19, 2014

Calculus
when the water has height y, its surface has diameter 4/6 y. So, v = 1/3 pi y^2 (2y/3) = 2/9 pi r^3 dv/dt = 2/3 pi r^2 dr/dt Now just plug in your numbers.
October 19, 2014

Calculus
Draw a diagram. If the boat is x meters from the pier, the rope haas length r, with r^2 = x^2+1 So, 2r dr/dt = 2x dx/dt when x=5, r=√26, so 2√26(-1) = 2(5) dx/dt dx/dt = -√26/5 so, the boat is approaching the dock at about 1.0 m/s Makes sense, since x and r ...
October 19, 2014

Math
No, (B). A occurs when the degree of deg(p) <= deg(q) C occurs where q(x) = 0 and p(x) ≠ 0 D occurs when deg(p) = deg(q)+1 where deg(p) is the degree of polynomial p(x) You were obviously grasping, since even your suggested answer did not match its description.
October 19, 2014

math
just google "pyramid area" and plug your numbers into the formula shown.
October 19, 2014

geometry
Y = ((5-1)/2,(5+5)/2) = (2,5) (-2,2) = ((X1+2)/2,(X2+8)/2) So, X = (-6,-4)
October 19, 2014

Calculus
the slope of the tangent line at x=a is 1/a. If the line goes through the origin, its equation is y = kx. Clearly, at x=e, the line through (e,1) has slope 1/e. So, a=e see http://www.wolframalpha.com/input/?i=plot+y%3Dlnx%2C+y+%3D+1%2Fe+x
October 19, 2014

math
each face is an isosceles triangle with base = 26 height = 35.4 I'm sure you know (a) how to find the area of a triangle (b) how many faces the pyramid has plug and chug
October 19, 2014

Calculus
y' = 4 * 2cos(x^3)(-sin(x^3))(3x^2) = 4(2)(cos 1)(-sin 1)(3) = -10.9 Looks like you got lost somewhere in the chain rule
October 19, 2014

algebra
since time = distance/speed, then if the first speed was x mph, 600/x = 600/(x+40) + 4 x = 60 Check: outbound: 60 mph: 10 hrs return: 100 mph: 6 hrs
October 19, 2014

Math
Assuming the ball's diameter is the smallest dimension of the block, it is 10cm in diameter. So, the fraction of the block occupied by the ball is (pi/6 * 10^3)/(14*12*10) = 31%
October 19, 2014

Trigonometry
draw a diagram. It is clear that tan 24° = (h-6)/70
October 19, 2014

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