Saturday
July 30, 2016

Posts by Steve

Total # Posts: 42,172

math
just plug in your basic equation of motion: s = vt + 1/2 at^2 Now just use your numbers for v and a and t.
June 27, 2016

maths
If one angle is x, then the other is x+18. So, x + (x+18) = 90
June 27, 2016

math
Looks like you found the easy way -- get someone else to do the work. p = 2.2 q p = r + 350000 q = r + .05(p+q+r) Now just find p,q,r and add them up.
June 27, 2016

Math3( Please Help Assignment Due)
you can enter your data at http://davidmlane.com/hyperstat/z_table.html
June 27, 2016

HISTory
why do you think? It was painted by a great master, during the Renaissance. It's a famous painting of that period, typical of the style then.
June 27, 2016

rio hondo
minimum at x = -1/14
June 27, 2016

Calculus - Discontinuity
It is only removable if f(x) is defined to be the same as the limit value. If f(x) were 7 at x=3, then that would plug the hole. But since it is defined to be a different value, it creates a jump which cannot be joined to fill the hole.
June 27, 2016

Calculus - Discontinuity
jump. f(x) = 2x+1 everywhere except x=3. Since the limit from both sides is 7, but f(3)=6, there's no way to remove that break.
June 27, 2016

Math2(Please Help Assignment Due)
I think you mean two congruent sides. The angles are Q=86 R=86 P=8 You know that q=r=44, so you just have to find p. Using the law of sines, p/sin8 = 44/sin86
June 27, 2016

Math( Please Help, Assignment Due)
Draw a diagram. Using the law of sines, the distance x you want is x/sin40 = 550/sin80
June 27, 2016

Calculus
everywhere except x=3, F(x) = 2x+1 Since 6≠7 you have a jump there. The limit from both sides is 7, but F is defined to be 6, and there's no way to close that gap.
June 27, 2016

calculus
6t dy/dt + y = √t y' + 1/6t y = 1/(6√t) You want an integrating factor: e^(∫1/(6t) dt) = t^(1/6) Now the equation becomes t^(1/6) y' + 1/6 t^(-5/6) y = 1/(6∛t) d(t^(1/6) y) = 1/(6∛t) t^(1/6) y = 1/4 t^(2/3) + c y = 1/4 √t + c/t^(1/6)
June 27, 2016

calculus
We have dA/dt = 2*4 - 1/(200+3t) A(0) = 100 and we want to find A(100) So, just solve the differential equation, and then plug in t=100, since at a net gain of 3 gal/min, the tank will be full at t=100.
June 27, 2016

Maths - eh?
Hmmm. Is it not 7P4 = 7!/3! ?
June 27, 2016

calculus
for any point on the curve, the distance z to (2,0) is z^2 = (x-2)^2 + (y-0)^2 = x^2-4x+4 + x+3 = x^2-3x+7 so, use z = √(x^2-3x+7)
June 27, 2016

Calculus - typo?
you dropped something out
June 27, 2016

Maths
√1700 = 41.23 So, any factor of 1700 less than that could be the length. So, you could have any integer dimensions from anything in this list: 1x1700 2x850 ... 25x68 34x50
June 27, 2016

math - woefully incomplete
an argument could be made for almost any number. One data point does not give much to go on.
June 27, 2016

math
120 is already rounded I think you left something out
June 27, 2016

Dahal
a wild-eyed political dissident
June 27, 2016

Dahal
every second v decreases by 1/2 m/s so, it takes 40 seconds to stop The distance covered during time t is s = 20t - 1/4 t^2 Now just plug in t=40
June 27, 2016

calculus
If they are changing at opposite rates, the slope is -1 dy/dx = 2x so when is that -1?
June 27, 2016

Algebra
x-y = 96 x+y = 300 solve that, or reason thusly: 150+150=300 difference is zero The difference is 96, so subtract 48 from one number and add 48 to the other: 102+198 = 300 difference is 96
June 27, 2016

programming
looks ok to me
June 27, 2016

Math
That's a salary bump twice a year, so 6000 + 50(2*5)
June 27, 2016

Urgent help here! Math
can't see the shaded area, but clearly the circle has radius 5.
June 27, 2016

physics
or, -1.5 km/hr/s
June 27, 2016

value
puqloDwI' ja'pu'vawq Dayep pe'vIl chop Ho'Du'Daj; pe'vIl Suq pachDu'Daj Ha'DIbaH puv juchyub yIyep bInDepSuHach vaQeHmuS ghombe' DanIDjaj
June 27, 2016

Maths
3a:2c
June 27, 2016

mathenatic
garbled English, but I think you want 6/2 (2a+5d) = 72 a+d = 7(a+64d) solve that for a and d, and then evaluate 10/2 (2a+9d)
June 27, 2016

Math
just go to any online unit conversion site. There are many good ones, such as http://www.onlineconversion.com/
June 26, 2016

Please Help ..!Math
1350/70/30 = 1710/x/28 x = 95
June 26, 2016

math
p * (1 - (11 + 1/9)/100) = 360 + 40
June 26, 2016

science
a = 2 + 1000/20
June 26, 2016

math
The question is mangled, but if you want to say that S17 = 359 S21 = 966 for an arithmetic sequence, then just solve 17/2 (2a+16d) = 359 21/2 (2a+20d) = 966 For a geometric sequence, you need a(r^17-1)/(r-1) = 359 a(r^21-1)/(r-1) = 966 In either case, the answers are not simple.
June 26, 2016

CALC
yeah, but how did you get it? Where did the 900 and 150 come from? With only 50 lb of salt at t=0, I don't see how it works. What is y measuring? I started out by reasoning that with no draining, ds/dt = 6 since since each minute 6 lbs of salt are added. OUCH! Typo, since ...
June 26, 2016

CALC
Why don't you explain your answer, and we can see whether your math is sound. Did you start (with s(t) being the amount of salt present) ds/dt = 1 - 6/100 s s(0) = 50 ? Surely you can see that 104.82 is way off. Even with no salt draining out, only 110 lb would be present ...
June 26, 2016

math
as a fraction of his money, he spent 1/4 + 2/5 + 1/6 = 49/60 So, 11/60 of his money was 55000 ...
June 26, 2016

Grammer
Extra credit: How does one express imperative mood in the 3rd person?
June 26, 2016

Math
2t = π/6 or 5π/6 or 13π/6 t = π/12 or 5π/12 or 13π/12 sum = 19π/12
June 26, 2016

Math
Why not show how you arrived at that value? If (sin+cos)=1.2, (sin+cos)^2 = 1.44 sin^2+2sin*cos+cos^2 = 1.44 1+2sin*cos = 1.44 sin*cos = .22 since (x+y)^3 = (x+y)(x^2-xy+y^2) (sin^3+cos^3) = (sin+cos)(sin^2-sin*cos+cos^2) = (sin+cos)(1-sin*cos) = 1.2 * 0.78 = 0.936
June 26, 2016

Math
11 rad/s * 1rev/2πrad * 30πin/rev = 115 in/s
June 26, 2016

Algebra
24+n = 2n
June 26, 2016

algebra , math
looks like it. Did you not check your answer? 2/3 of 33 is 22 22+7 = 29 We have a winner!
June 26, 2016

math
anything is hard until you are good at it. You just need more practice. Think of things you like. You spend lots of time doing them. Same thing for math. Rather than avoiding it, find someone you like who is good at it, and work together.
June 26, 2016

MATH 3
3000 * 0.115 * 3
June 26, 2016

Math
think a minute what can you multiply twice by 3 and still be less than 10?
June 26, 2016

geometry
lateral area is four triangles with base 11 and altitude 15 Surface is that area plus the square base. I assume you can find the area of triangles and squares...
June 25, 2016

geometry
No, the 20x15 lot costs 300*8 = 2400 So, the larger lot costs 2400*2*2 = 9600
June 25, 2016

Math
so, if Karla's age is x, Ama is x+3 Daniel is x+3+2 = x+5 So, adding them all up, x + x+3 + x+5 = 32 3x+8 = 32 3x = 24 x = 8 Their ages are 8,11,13
June 25, 2016

value
planes fly on headings, not bearings. Use the law of cosines: CA^2 = AB^2 + BC^2 - 2*AB*BC*cos(41+50)° You can easily get AB and BC using distance = speed * time.
June 25, 2016

math
finite: 1,5 infinite: 2,3,4
June 25, 2016

ALGEBRA
since time = distance/speed, if the man's walking speed was w, then we have 180/12w - 3 = 6/w w = 3 so, he drove at 36 mi/hr, doing the 180 miles in 5 hours.
June 25, 2016

algebra
http://www.jiskha.com/display.cgi?id=1466735810
June 25, 2016

English
#1 and #2 are the same #3 and #4 are the same, but stronger than 1 & 2.
June 25, 2016

Math
sin37° is very close to 0.6, so cut 'em some slack. The 6-8-10 triangle has one angle of 36.87° I assume they want other trig functions using that triangle.
June 25, 2016

science
volume = mass/density
June 25, 2016

science
density = mass/volume = 1.75g/2.5cm^3
June 25, 2016

science
Beneath the surface, gravity is basically a linear function of the radius. So, at 1/100 the radius, g is reduced by a factor of 1/100 See the discussion here: http://physics.stackexchange.com/questions/99117/why-gravity-decreases-as-we-go-down-into-the-earth
June 25, 2016

math
If C was in the business for x months, then the weighted investment is (20000*12 + 40000*9 + 100000x) * x/12 = 55000 x ≈ 1, so C joined after about 11 months
June 25, 2016

geometry
why post such questions that can be simply evaluated on any decent calculator? Or by google? If you mean tan^-1(9) then that is 83.65° sin^-1(0.62) = 38.32°
June 25, 2016

geometry
no idea. Where the heck is U?
June 24, 2016

Mathematics
cc = 0
June 24, 2016

Math HELPPPPP
(a) x/7 + y/11 = 1 y/11 = -1/7 x + 1 y = -11/7 x + 1 The answer is -11/7, not -11/7 x (b) You have a point and a slope, so use the point-slope form! y-3 = -5/3 (x-2) Now just rearrange that into slope-intercept form as needed.
June 24, 2016

algebra
well, you know that y = vt - 4.9t^2 max height is at t = v/9.8
June 24, 2016

geometry
42
June 24, 2016

physics 1
x = 2t^3 v = 6t a = 6 To find an average, just divide the change by the interval. (a) x(1) = 2 x(2) = 16 avg v = ∆x/∆t = (16-2)m/(2-1)s = 14m/s I think you can handle the rest, no?
June 24, 2016

CHEMISTRY - My Bad
yeah - sorry. I read some of your other posts and saw what was going on.
June 24, 2016

CHEMISTRY
You must keep the ions in their proper proportions. NO3 is the ion, so changing it to NO6 is bogus. Maybe you should try (NO3)2 Or, if NO is the ion, then (NO)3 would give you three of them.
June 24, 2016

CHEMISTRY
not unexpected, since there is no Carbon present. Did you try Nitrite? Carbonate is CO3
June 24, 2016

Math
just add 3 to x and 6 to y in each coordinate pair
June 24, 2016

math
Assuming that Tn = ar^n that means that T1 = a Tn+1 = Tn * r
June 24, 2016

math
the hectares answer is way off. Each mi^2 is 259 hectares The gas savings is 33.33-25 = 8.33 so each of you would save $4.16
June 24, 2016

Math (pre-celc 12)
Nope. You didn't do what I told you. (f+g)-(f-g) = 2g so, 2g = (10-3x)-(5x-14) 2g = 24-8x g = 12-4x Now just check to be sure that your answers work: f+g = (x-2)+(12-4x) = 10-3x now check f-g the same way
June 24, 2016

math
a = (√3-√2)/(√3+√2) b = (√3+√2)/(√3-√2) Clearly ab=1 Doing the squares directly is a bit cumbersome, so let's rationalize the denominators: a = (√3-√2)^2 = 5-2√6 b = (√3+√2)^2 = 5+2√6 Now ...
June 24, 2016

Math
clearly, real-world distances cannot be negative. You have to use a little common sense along with the math. Even if you allowed for negative distance, that would mean the boat burrowed into the cliff!
June 24, 2016

science
Nope. p = mv 0.5 = 50v 0.01 = v v = 0.01 m/s Try redoing your calculation and you will see that the units do not wind up as m/s.
June 24, 2016

Math
w+y = 30 9.95w + 13.50y = 351.75 Now just solve for w and y
June 24, 2016

math
500 e^(7*.04)
June 24, 2016

math
Note that if x = 5-2√6 1/x = 5+2√6 Now just crank it out
June 24, 2016

math
just plug and chug: #(#3) = #(3^2-3) = #6 = 6^2-6 = 30
June 24, 2016

maths
multiply top and bottom by 5-√3: (5-√3)/(5+√3) = (5-√3)^2/22 now just expand that out to see a and b.
June 24, 2016

SIMULTANEOUS EQUATION
5x^2-5x-63 = 5(x^2-x) - 63 Recall that (x-a)^2 = a^2-2a+a^2 Here we have 2a = 1, so a = 1/2. So, add and subtract 1/4 * 5 = 5(x^2-x + 1/4) - 63 - 5/4 = 5(x - 1/2)^2 - 267/4 To get the roots, set that to zero: 5(x - 1/2)^2 - 257/4 = 0 5(x - 1/2)^2 = 257/4 (x - 1/2)^2 = 257/20 x...
June 24, 2016

Simultaneous equation
From the first equation, x = (3y+14)/5 Use that in the other equation to get 3(3y+14)/5 + 5y = 18 9y+42 + 25y = 90 34y = 48 y = 48/34 = 24/17 = 1 7/17 x = (3y+14/5) = (72/17 + 14)/5 = 310/85 = 3 55/85 = 3 11/17 You could also have used other substitutions for x, or using the ...
June 24, 2016

maths
The first digit cannot be zero, so it must be 1,2,3,4 Now just start listing them: 103 112 ... 310 400
June 24, 2016

math
you need to remember that you can always multiply by 1 without changing anything. The trick is to make sure that the units cancel correctly 1 ton = 2000lb that means that 1ton/2000lb = 2000lb/1ton = 1 8.9*10^5ton * 2000lb/ton * 1kg/2.204lb = 8076*10^5kg or, 8.076*10^8kg or,you...
June 24, 2016

math
1st two are ok 2.9x10^11 = 0.029x10^13 Now you can add them to get 3.729 x 10^13
June 24, 2016

Pre-Cal
each inverse trig function has a principal domain. Review those. tan 5π/6 = -tan π/6 = -1/√3 but, tan^-1(-1/√3) = -π/6 cos -π/4 = cos π/4 = 1/√2 but, cos^-1(1/√2) = π/4
June 24, 2016

Math
or, you are reducing the concentration by a factor of 4/10, so you must increase the volume by a factor of 10/4. 10/4 * 40 = 100 So, you must wind up with 100ml, by adding 60ml of water.
June 24, 2016

Math year 10
since s=k-5, the product is ks = k(k-5) or s(s+5)
June 24, 2016

Math
4/80 = 5% of the caught fish were tagged. So, the 70 tagged fish must be about 5% of the total population.
June 23, 2016

algebra
f(1.5) = -4.96 f(1.8) = +0.77 Since f is continuous on the interval, and 0 is between -4.96 and +0.77, f must be zero somewhere in that interval. It cannot change from negative to positive without going through zero.
June 23, 2016

Physics
find v, the speed of sound. If the depth of the well is y, then the time taken for the sound to come back is y/v Using the equation of motion, we have 4.9t^2 = y Thus, the time it takes to hit the water is √(y/4.9) Adding up the times, we have √(y/4.9) + y/v = 0.6 ...
June 23, 2016

Pre-Cal: Word Problem
can you see how unhelpful that response is? What did you enter, and why was it wrong?
June 23, 2016

Pre-Cal: Word Problem
on the interval [-90,90] sin^-1 is 1:1 For cos^-1, the domain is [0,180] But you probably want radians instead.
June 23, 2016

Math
(a) using shells, v = ∫[1,3] 2πrh dx where r = x+2 and h=y=ln(x) using discs, v = ∫[0,ln3] π(R^2-r^2) dy where R=5 and r=x+2=2+e^y (b) use the same ideas with a horizontal axis. Just keep in mind the volume of a disc (or a washer with a hole inside) and a...
June 23, 2016

maths
100u+10t+h = 100h+10t+u - 396 u-t = t-h solve that and you get t = h-2 u = h-4 h = t+2 = u+4 since no digit is zero, we can have 531 642 753 864 975
June 23, 2016

math
18f = 33g f/g = 33/18 = 11/6
June 23, 2016

Physics
Hmmm. your math looks good. Using the 5.8R and 19.6 I get (2)(3.14)(5.8)(6.4 * 10^6)(1.22) = 284,398,592 which agrees with their rounded answer for distance. Divide that by 86400 seconds and it gives a speed of 3291 m/s, which is pretty close. Is your answer anywhere near ...
June 23, 2016

Physics
figure the radius R of the orbit The distance traveled in one orbit is thus 2πR Now just figure how many orbits it makes in 24 hours. That will give the total distance traveled. Then just divide that by the time (86400 s) to get the speed.
June 23, 2016

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