Wednesday
May 25, 2016

Posts by Steve

Total # Posts: 40,790

math
3/200 = 1.5/100 = 1.5%
May 3, 2016

Math
tanx/sinx = 1/cosx cosx=0 at odd multiples of pi/2. So, that is where you have asymptotes. cosx changes sign at those points, so also does your graph.
May 3, 2016

math
depends on the area of the base. Divide the volume by the area to get the height.
May 3, 2016

math - eh?
huh?
May 3, 2016

math - Correction.
that is an obtuse angle. I'd say 0° < d < 90°
May 2, 2016

Maths
The three numbers will therefore be close to 21.98. So, I'd say they'd be 21,22,23 whose product is 10626
May 2, 2016

math
480ft/30s * 60s/min = 960 ft/min
May 2, 2016

math
not so. you have found d/dt (dy/dx), but you want d/dx (dy/dx) = d/dt(dy/dx) / dx/dt = -1/(1+t)^2 / e^t = -1/((1+t)^2 e^t)
May 2, 2016

TRIGONOMETRY2
can't use google? 1st hit led to http://www.cut-the-knot.org/proofs/2Colors2Points.shtml#solution
May 2, 2016

TRIGONOMETRY
√(x+b)-√(x-a) >= √(x+a)-√(x-b) since x>=a>=b, we have x+b >= 2b x-a >= 0 x+a >= 2a >= 2b x-b >= x-a see what you can do with that
May 2, 2016

Math
the ratios are: length: 11/33 = 1/3 width: 7/28 = 1/4 so, not similar
May 2, 2016

math
not quite. log(x^2) = 2logx 150 = 3*100/2, so log 150 = log3 + 2log10 - log2 75 = 3*(10/2)^2, so log75 = log3 + 2log10 - 2log2 or, since 75 = 150/2 log75 = log150-log2 as above
May 2, 2016

Probability
1/15000 (1000 + 2*300 + 20*10) = 3/25
May 2, 2016

Math
there is no limit. There must be some other considerations.
May 2, 2016

Geometry
well, just check. a sphere with diameter d has volume π/6 d^3 3*(π/6)(5^3) = 375π/6 (π/6)*8^3 = 512π/6 π/12 * 10^3 = 500π/6
May 2, 2016

calculus
94 ∑ k k=3 assuming you meant ... 144, 12 ∑ k^2 k=3
May 2, 2016

Algebra
y=5x
May 2, 2016

pre-cal
as they said, the total area is xy as for the print area, that is (x-2)(y-3) = 26
May 2, 2016

calculus
maximize p=x(30-x)-100-6x subject to x >= 10 x <= 20 the profit is revenue-cost, so p(x) = x(30-(x-10)) - 100 - 6x = -x^2+34x-100 dp/dx = 34-2x dp/dx=0 at x=17
May 2, 2016

calculus
this is just the chain rule in reverse. G'(x) = cos(x^2) (2x)
May 2, 2016

calculus
change all the t's to x^2, then multiply by (x^2)' G(x) = cos(x^2)(2x)
May 2, 2016

math
it is a function whose graph is s straight line.
May 2, 2016

calculus
Sketch the region. It has vertices at (0,0), (2,0), (4,2) You can get the area by using vertical or horizontal strips. Using vertical strips, they all lie below the curve √x, but the lower boundary changes from y=0 to y=x-2 at x=2. So, the area is ∫[0,2] √x ...
May 2, 2016

math
as usual, v = Bh = 20*10 = 200 cm^3 note that the area of the base must be in cm^2, not just cm.
May 2, 2016

Math
You have only listed 4 side lengths, so I'm not clear. But, to get the area, divide it up into triangles, and maybe rectangles, if there are any. Then just add up the areas of the pieces.
May 2, 2016

math
the base is 139.2/9.6 = 14.5 since all sides are the same, the perimeter is 4*14.5 = 58
May 2, 2016

algebra
(17-1)/(2-(-2)) = 16/4 = 4
May 2, 2016

calculus too hard help
Let's pick up at lny = x ln(y) 1/y y' = ln(y) + x/y y' y' (1/y - x/y) = ln(y) y' = y*ln(y)/(1-x) I'd suggest not looking too hard for a pattern. Pop over to wolframalpha.com and try entering x^x, then x^x^x, then x^x^x^x, and so on. The derivatives ...
May 2, 2016

Math
Thank you Reiny. That makes perfect sense to me. Next time I post a question I will think a little harder to possible ways of working questions like this. 😀😀
May 2, 2016

Math
When a telephone exchange is established, there are 10,000 new phone numbersto use(i.e. 722-0000 to 722-9999). Of these 10,000 phone numbers, how many do not contain the digit "9"? I know I can do it this long way, but how do I do it in a shorter more reliable way. ...
May 2, 2016

Calculus - urgent
Consider the mass as a bunch of horizontal strips, each with area (x2 - x1) dy and thus mass (x2-x1)y dy = y(√(1+2y/3) - (2y^2-y)) dy Now just integrate from 0 to 1.0989
May 2, 2016

trigonomentry...Very hard
theta, not tita. let x = 3tanθ x^2 = 9tan^2θ 9+x^2 = 9+9tan^2θ = 9sec^2θ √(9+x^2) = 3secθ so, draw a right triangle. Since tanθ = x/3, those are the two legs, and the hypotenuse is √(9+x^2) Now you can write down sinθ and cosθ
May 2, 2016

Geometry (answer please)
#1. well, each wire is the hypotenuse of a right triangle, with legs 16 and 10√2 back later for #2.
May 2, 2016

Math
surely, 3+3+3 feet, no? assuming the ribbon is to go once around the edges of the blanket...
May 1, 2016

Math
since u.v = |u||v|cosθ we must have cosθ = -1. In other words, v = -u
May 1, 2016

Algebra 1
B is good.
May 1, 2016

math
If you're using logs base 10, recall that log(32) = log(10*3.2) = log(10)+log(3.2) = 1+log(3.2) So, just look up log of 3.2 and add 1. Whoa - who uses tables these days?
May 1, 2016

Plane trigonometry
I don't know what "the five points" are, but here's the graph: http://www.wolframalpha.com/input/?i=2sin%28pi*%28x%2B1%2F2%29%29%2B1
May 1, 2016

trig
I'll use x for ease of typing tan(x)/(tan(2x)-tan(x)) tan(x)/((2tanx)/(1-tan^2(x))-tan(x)) tan(x)/((tanx(2/(1-tan^2(x)) - 1) 1/(2/(1-tan^2(x)) - 1) (1-tan^2(x))/(2 - (1-tan^2(x)) (1-tan^2(x))/(1+tan^2(x)) (1-tan^2(x))/sec^2(x) (1-tan^2(x))cos^2(x) cos^2(x)-sin^2(x) cos(2x)
May 1, 2016

Algebra
you are correct.
May 1, 2016

MEASUREMENTS
15m^2 * (3.28ft/1m)^2 * 1bag/20ft^2 * $2.00/bag = $16.14 you said M^2, then used YD^2. I used meters, but you can fix it. Your units do not work out right, and you lost the 15
May 1, 2016

Exponential Modeling
on the other hand, given the topic of the posting, 0.10(1+r)^40 = 1.25 (1+r)^40 = 12.5 1+r = 1.065 r = 6.5% per year
May 1, 2016

MATH
The scores are x x x x x x x x The median is 5, so they are x x x 5 5 x x x or x x x 4 6 x x x or 3 3 3 3 7 7 7 7 In the first case, 5 goals are scored. Otherwise, we need not have any scores of 5.
May 1, 2016

math
this is discussed at http://mathforum.org/sum95/suzanne/whattess.html google is your friend. Use it.
May 1, 2016

MATH- HELP PLEASE. IM LOST
the other side is either 3.7Ø or 3.7/Ø
May 1, 2016

Geometry ( helllppp pleaaassse )
#1. How can working with a single point on the ceiling tell anything about the length of the ceiling? #2. Drop the ladder to the floor, and mark where it hits. The use the ladder to construct a hexagon. Two of the main diagonals intersect at the center of the hexagon, just ...
May 1, 2016

Exponential Modeling
100 * (1/2)^7
May 1, 2016

Exponential Modeling
2000 * (1/2)^x
May 1, 2016

Exponential Modeling
p = 1013 * .88^x check for typos
May 1, 2016

Math
subtract 32 and multiply by 5/9 C = 5/9 (F-32)
May 1, 2016

Algebra
try this useful site: http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html
May 1, 2016

Math
5/6 * 1/2 = 5/12 you might as well ask, what is 1/2 of 5/6?
May 1, 2016

Math
a + a+d + a+2d = 24 a+3d + a+4d + a+5d = 51 now simplify the equations and solve for a and d.
May 1, 2016

Geometry
If the foot of the ladder started out at x ft away from the wall, then we know that the length of the ladder is 2x ft. With a 45° angle, then the two legs are x+8 ft, and the length of the ladder is (x+8)√2. So, now we have 2x = (x+8)√2 x(2-√2) = 8√...
May 1, 2016

Solid Mensuration
circles can be packed in many ways. If they are in a rectangular lattice then they may be in a 2x3 array, in which case, each circle's diameter is 1 foot. Surely by now you have made some attempt to solve the problem...
May 1, 2016

Matthhh
the straight-line distance is √(60^2+6^2) = 60.3 ft, so ...
April 30, 2016

Algebra
since there is a walkway on both sides, each dimension is increased by 2x. A(x) = (20+2x)(15+2x)
April 30, 2016

Algebra
since time = distance/speed, 6/(90-x) + 6/x = 4.5 x ≈ 1.35 km/hr
April 30, 2016

math
1 2 3 5 6 6 6 so, it can be 1. or even 1 5 5 5 5 5 6
April 30, 2016

Discrete Mathematics
26!/(8!12!6!) wow - who'd have thought that the entire set of books would contain only three different titles?
April 30, 2016

CES
1*22 + 9x = 8(x+22)
April 30, 2016

MATH
volume = 50*10*20 cm^3 1 liter = 1000 cm^3
April 30, 2016

algebra
I suspect the subtraction problem is 2x^2+5x-10 3x^2-x+9 ----------------- -x^2+6x-19
April 30, 2016

math
42 is the answer to the Ultimate Question of Life, the Universe and Everything -- surely it answers your feeble inquiry! Actually, I have no idea what you're talking about. which columns are you talking about? The only thing I can think of is that the line of cars looks ...
April 30, 2016

math
42
April 30, 2016

Math
well, 1 meter is 100 cm. So, how much is still needed?
April 30, 2016

rio claro west secondar
0.4^2 * 3.7 = 0.16 * 3.7 = ?
April 30, 2016

math
bzzt. The new value is 120% of the old one, so it increased by 20%.
April 30, 2016

math
3 of 8 = 3/8 = .375 = 37.5% t2o killed leaves 6 to share, so adjust the fraction. then subtract to find the change.
April 30, 2016

math
well, what are the nearby multiples of 500? ... 29,000 29,500 30,000 ... which is closest?
April 30, 2016

maths
you kidding me? You can't count by twos?
April 30, 2016

Maths
LCM(30,60,x) = 1500 30 = 2*3*5 60 = 2^2*3*5 1500 = 2^2*3*5^3 x could be 5^3 = 125 or any multiple of 25 consisting only of 2,3,5 as factors GCF(30,60,x) = 10 so, 125 is out, but 250 is in LCM(30,60,250) = 1500 GCF(30,60,250) = 10
April 30, 2016

Math
what is the difference between 6 and 10? How did you find it? Do the same step with the numbers above recall how to subtract negative numbers: 10 - (-5) = 10+5 = 15
April 30, 2016

Solid Mensuration
The diameter of the circle is 12 cm. The quadrilateral consists of two congruent triangles, with base 12 and altitude 4. So, its area is 48 cm^2
April 30, 2016

Maths
what is the difference between 6 and 10? How did you find it? Do the same step with the numbers above recall how to subtract negative numbers: 10 - (-5) = 10+5 = 15
April 30, 2016

GEOMTRY
1 yard = 3 feet 1 yard = 0.9144 meters 1 foot = 12 inches 1 foot = 0.3048 meters now just do the conversions
April 30, 2016

Calculus
If the rectangle has height x, then it has vertices (x,0), (x,x), ((20-x)/3,x), ((20-x)/3,0) so, its area is a = x((20-x)/3-x) = 20x/3 - 4x^2/3 da/dx = 20/3 - 8x/3 da/dx=0 at x=5/2, and a(5/2) = 25/3
April 30, 2016

Homework Dump
No ideas on any of these??
April 29, 2016

Homework Dump
no ideas on any of these?
April 29, 2016

Algebra
that is correct.
April 29, 2016

Algebra
nope. Subtract the exponents. 10^7/10^3 = (10^3 * 10^4)/10^3 = 10^4 or, more brute-force, 10*10*10*10*10*10*10 -------------------------- = 10*10*10*10 10*10*10
April 29, 2016

College Algebra
4-3(x+1)=2x 4-3x-3 = 2x 4-3 = 5x 1 = 5x x = 1/5 15x^2 + x = 2 15x^2 + x - 2 = 0 x = (-1±√(1+120))/30 = (-1±11)/30 = -12/30,10/30 = -2/5, 1/3 √(4x+5) = x 4x+5 = x^2 x^2-4x-5 = 0 (x-5)(x+1) = 0 x = -1, 5 only x=5 is a solution, since √(-4+5) = &#...
April 29, 2016

Algebra
6/(√3+2) = 6(√3-2)/-1 = 12-6√3 or, B
April 29, 2016

Algebra
6/(√3-2) recall that (a-b)(a+b) = a^2-b^2 multiply top and bottom by (√3+2) and you have 6(√3+2) ---------------- (√3-2)(√3+2) = (6√3+12/(3-4) = -6√3-12 check your text for typos. It looks like B except for the extra minus sign.
April 29, 2016

Math/Computer
try google, something like graphs ms word or something. (3,0) is just a point. Seems like a strange project.
April 29, 2016

Math
Since you have described no experiment, I will have to rely on the theoretical probability of 1/6, making my answer 50.
April 29, 2016

Algebra
Nope. What did you do? And use some parentheses: -3/(x+2) - 5/(x+3)
April 29, 2016

math
list the possibilities: P(WWW) = 2/4 * 1/3 * 0/2 P(BWW) = 2/4 * 2/5 * 1/4 ... P(BBB) = 2/4 * 3/5 * 4/6 then add up all the ones where the 3rd ball is black.
April 29, 2016

@Need Help
The subscripts are a trick of HTML. Most of the codes do not work on this site, but the sub and /sub tags work. For superscripts, the sup and /sup tags work. enclose the words in <> brackets to make them into HTML tags.
April 29, 2016

@Reiny
Some of these blokes use log6^(1/36) to mean log6(1/36), which is indeed -2 #2 ln(1/e^4) = ln(e^-4) = -4 #3 ok #4 ok #5 since the other logs specify a base, this must be just a common log, and log 10^8 = 8 #6 log3√3 = log33^(1/2) = 1/2
April 29, 2016

math -.-
just divide each term in the numerator by the denominator: (x^4+5x^3)/(3x^2) = x^4/(3x^2) + 5x^3/(3x^2) = x^2/3 + 5x/3 or, 1/3 x^2 + 5/3 x
April 29, 2016

Calculus
πr^2h = 200, so h = 200/πr^2 The cost is thus c = .02*2πrh + .06*2πr^2 = .04πr(200/πr^2) + .12πr^2 = 8/r + .12πr^2 dc/dr = -8/r^2 + .24πr dc/dr=0 when r ≈ 2.2 Now just crank out h and c
April 29, 2016

Math Check
Surely there should be π somewhere in the answer. And what is the shape of the solid? You have given a semi-circular base, but no other info.
April 28, 2016

Math
n+d+q = 22 5n+10d+25q = 175 n = 3d now crank it out
April 28, 2016

Math
just solve for t in -16t^2 + 120t+ 50 = 10 probably the quadratic formula will be helpful.
April 28, 2016

Calculus
Draw a side view. If the cylinder has radius r, and height h, then r^2+h^2 = 6^2 the volume of the cylinder is thus v = πr^2h = πr^2√(36-r^2) now just find dv/dr=0 and thus the maximum volume's radius.
April 28, 2016

Calculus
if the squares are of side x, then v = x(12-2x)^2 = 4x^3-48x^2+144x dv/dx = 12x^2 - 96x + 144 = 12(x-2)(x-6) so, v has a max at x=2.
April 28, 2016

Geometry
if the lateral area is 232pi, then pi rs = 232pi rs = 232 s^2 = r^2+h^2, so s = √(r^2+441) r√(r^2+441) = 232 r = 9.97 So, let's say r=10. Then a = 10√541 = 232.6 If the total area is 232pi, then use the adjusted formula for that.
April 28, 2016

Maths
the scale is 1cm:5km the area scale is thus 1cm^2:25km^2 multiply that by 405, and you have 405cm^2 : 10125km^2
April 28, 2016

homework
I assume the axis of rotation is the line y=49. So, the shells have thickness dy, and v = ∫[0,49] 2πrh dy where r = 49-y and h = (7+√(49-y))-(7-√(49-y)) v = ∫[0,49] 2π(49-y)((7+√(49-y))-(7-√(49-y))) dy = 26891.2π you can check...
April 28, 2016

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