Thursday
July 28, 2016

Posts by Steve

Total # Posts: 42,140

General Math
since pure juice is 100% juice, add up the amounts of juice: .50(6) + 1.00(x) = .75(6+x)
July 7, 2016

physics PS
Oops -- v = 2/3 t^3 i + 2/3 t^2 j
July 7, 2016

kashinath palod
FF = ma = 6t^2i + 4tj Since m=3, a = 2t^2i + 4/3 t j so, v = 2/3 t^2 i + 2/3 t^2 j
July 7, 2016

Calculus
well, sin^2(x) = 1/2 (1-cos(2x)) that should be easy to integrate, right?
July 7, 2016

maths
I have never heard of the word kharch, but the apple's share is 5/(6+10+5) = 5/21
July 7, 2016

math
well, ADB is also an isosceles right triangle with sides of 5. So, its hypotenuse is AB = 5√2 that help?
July 7, 2016

Math
Well, the 1st term in the rth group is 1,2,4,7,11,... = 1+ 0,1,3,6,10 = 1+ r(r-1)/2 That should get you started.
July 7, 2016

Math
looks good
July 7, 2016

pre cal
6(x^2 - 2/3 x + 1/9) = 6(x - 1/3)^2
July 7, 2016

Pre-Cal
(csc θ − sin θ)/(cos θ) = (1/sinθ - sinθ)/cosθ = (1-sin^2θ)/(sinθ cosθ) = cos^2θ/(sinθ cosθ) = cosθ/sinθ = cotθ
July 6, 2016

Pre-Cal
(sin^2 + cos^2)/cos = 1/cos
July 6, 2016

java program
letter = (n>=90) ? "A" : (n>=80) ? "B" : (n>=70) ? "C" : (n>=60) ? "D" : "E";
July 6, 2016

Algebra
check the slopes. If their product is -1, the lines are perpendicular. That is, if one slope is the negative reciprocal of the other.
July 6, 2016

Math
Thunk of it using actual numbers. If he can mow the lawn in 4 hours, how much in 2 hours? 2/4 So, it will take him 2/x hours. If it takes him x hours, he does 1/x of the job in 1 hour. So, twice that, or 2/x in 2 hours.
July 6, 2016

math
ever hear of actual math symbols? 3√5 - 2√7 + √245 - √28 3√5 - 2√7 + √(49*5) - √(4*7) 3√5 - 2√7 + 7√5 - 2√7 10√5 - 4√7
July 6, 2016

MATH HELP
In 30 minutes, the first bus has gone 39 miles The 2nd bus goes 15 mi/hr faster. So, how long does it take to cover the extra 30 miles? It's the same as if the 1st bus stopped 30 miles away, and the 2nd bus drove 15mph to meet it.
July 6, 2016

Chemistry
sure looks like D to me twice the value, opposite direction
July 6, 2016

math
what, you cannot add 600+3200 ?
July 6, 2016

Normal Distribution
you can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html
July 6, 2016

math
not sure what the scaling has to do with anything, as the scaled polygon is never mentioned. However, it should be easy to convince yourself that such a scaling does not change any of the slopes or angles involved.
July 6, 2016

Math
yes, it can. Because to be even f(-x) = f(x) This is true only (and always) if all the exponents are even.
July 6, 2016

Math
the highest exponent is the degree the order of a root is the number of times it appears. So, you have three roots of degree 1. Any polynomial of degree n has exactly n roots, though all may not be unique (order 1).
July 6, 2016

algebra 2-1
x=42
July 6, 2016

Pre Calculus
again, only one possible choice, since e^1 = 2.718 e^2 = 7.389 e^3 > 16
July 6, 2016

Pre Calculus
x = 5/2 Now if you mean 2^x = 5 The answer should be clear, since 2^1 = 2 2^2 = 4 2^3 = 8
July 6, 2016

Math
since time * speed = distance, and the two distances are the same, 60t = 70t + 3/2 find t, then use that to get the distance
July 6, 2016

maths
make that 100° (130-30)
July 6, 2016

maths
use the law of cosines: QR^2 = PQ^2 + PR^2 - 2 PQ PR cos 130
July 6, 2016

Math - eh?
between 20,000 and 40,000 2xxxx 3xxxx 4xxxx mumble mumble My hundred digit is the sum of my ten thousands digit. ???
July 6, 2016

math
The minute hand has advanced 25/60 = 5/12 of a circle, or 150° The hour hand at 6:00 is at 180°, and it has advanced 5/12 of the way to the 7, or 5/12 * 30 = 12.5° So, the angle is 12.5+30 = 42.5°
July 6, 2016

math
no drawing here
July 6, 2016

math
at what time?
July 6, 2016

Math (Analytic Geometry)
Assuming you just want verification of your results, 1. y + 5/2 = 6/5 x 2. (x+8)^2+(y-8)^2 = 4((x+2)^2+(y-2)^2) or, x^2+y^2 = 32 3. Clearly this is the ellipse with foci at the two points, and a=6, c=4, b^2=20 x^2/36 + y^2/20 = 1 see http://www.wolframalpha.com/input/?i=...
July 6, 2016

See a Therapist
You clearly have a split personality and can't even tell that you keep posting the same problems again and again.
July 6, 2016

Analytic geometry
they lie on the perpendicular bisector of the line between the two points. That line has slope -5/6, so its perpendicular has slope 6/5 The midpoint of the line segment is (0,-5/2), so the line you want is y + 5/2 = 6/5 (x-0)
July 6, 2016

MATH
you need to cut off a slice 2√5 wide.
July 6, 2016

arithmetic sequence
A9 = A1 + 8d
July 6, 2016

arithmetic sequence
there are 4 terms past the first, so divide 92/4 to get the difference between terms
July 6, 2016

arithmetic
10000
July 6, 2016

math
what are the factors of 65? 5 and 13 looks like they work
July 6, 2016

Math
a+2d = 8 a+8d = 3*8+2 so, a=2 and d=3 Now you want S19 = 19/2 (2*2 + 18*3)
July 6, 2016

Meths
since distance = speed * time, 60t + 11/2 = 70t Now you have the time it takes, so you can find the distance.
July 6, 2016

Math
vertical asymptotes: y = 1/((x+6)(x-7)) y(6) = 0, so y = (x-6)/((x+6)(x-7)) horizontal asymptote at y = 10/9 needs a quadratic on top, so we could have y = (10/9)(x-6)^2/((x+6)(x-7)) but that does not really cross the x-axis at x=6, but just touches it. So, how do we get that ...
July 6, 2016

Phisics
measured in Joules. So, look up the definition of a Joule.
July 5, 2016

chem 121
just plug in your formula PV = nRT n = PV/RT n is the number of moles. Now multiply by A, Avogadro's constant to get the number of molecules. Or, since R = kA, n = PV/kAT so nA = PV/kT gives the number of molecules
July 5, 2016

math-steve
Hmmm. I drew a tree with all possible outcomes, but I forgot to weight each branch with its probability. Try doing that and see what happens. I'll try to get back later.
July 5, 2016

Science
at time t, s = 20t + 1/2 a t^2 so, we can find a by solving 20*30 + 1/2 a * 30^2 = 1200 a = 4/3 m/s^2 v = 20 + at = 20 + 4/3 * 30 = 60 m/s
July 5, 2016

Math
I'll assume that s is the length of a side. After the borders are discarded, an (s-2)x(s-2) square remains. There are 2(s-2)-1 = 2s-5 squares on the diagonal, so the remaining squares number (s-2)^2 - (2s-5) = s^2-6s+9 = (s-3)^2 you can easily check this for small s.
July 5, 2016

Pre Calculus
Since log(xy) = log(x) + log(y) regardless of the base, and considering the chance of typos, I'd go with (e)
July 5, 2016

science
sets of vectors? 10,20,30 are just three scalars. Try again.
July 5, 2016

Math
well, 15 1/2 = 15.5 So I'd guess 2.155 but that's certainly an unusual way to express a value. In fact, I'd guess it's a typo. I've never seen a mixture of decimal and fraction like that.
July 5, 2016

Maths
use your sum-to-product formulas: cosB-cosA = 2 sin (A+B)/2 sin (A-B)/2 cosA+cosB = 2 cos (A+B)/2 cos (A-B)/2 now just divide
July 5, 2016

math
1/10 to end up with exactly 27 6/10 to end up with at least 27 4/10 to lose
July 5, 2016

math
22+25-2
July 5, 2016

Pre-Calculus 11
2∛3 + 5∛3/4 = ∛3 (2+5/4) = ∛3 (13/4) or maybe 2∛3 + 5∛(3/4) = (5+2∛4)∛(3/4) = 1/2 ∛3 (4+5∛2) -12√11 + 5√11 = -7√11 Other than that I don't see much joy
July 4, 2016

math
875 * (1+2)
July 4, 2016

Math of investigation
Hmmm. I originally rejected the idea that the centers would lie on the diagonal, because I thought the circles would overlap or not fill the maximum area. I'm not sure how your equation comes about, but it appears you have solved the problem.
July 4, 2016

Object Oreinted Programming in java
not much object usage there. Just about a dozen lines of code, mostly I/O.
July 4, 2016

Economics/Finance
You don't say what he started with. Assuming $2000, at the end of year 2 he has 2000*1.05^2 at the end of year 4, he has 2000*1.05^4 + 2000*1.05^2 so, after 20 years, that's 10 investments, totaling 2000 (1.05^20 + 1.05^18 + ... + 1.05^2) Now, 1.05^2 = 1.1025 so that&#...
July 4, 2016

Pre Calculus @Reiny
Good job with the formatting!! Did you post somewhere in the past as a scratchpad?
July 4, 2016

Pre Calculus
A little synthetic division shows that f(x) = (x-(6+√6))(x^2+(√6-5)x+(√6-6))+2 I leave it to you to verify that f(6+√6) = 2
July 4, 2016

Math
a = πrs where 2πr = 132 s^2 = r^2+h^2
July 4, 2016

geometry
Draw a diagram. If the hat's radius is r, then r^2+r^2 = 15^2 and the diameter is just 2r
July 4, 2016

Math
just multiply the volume of metal by its density to get the mass: cm^2 * g/cm^3 = g You know that the volume of a sphere of radius r is v = 4/3 πr^3 so, to get the volume of metal, just subtract the volume of the empty inner sphere from the outer sphere.
July 4, 2016

Math
the mean of 2,3,5 is 10/3 So, to have a mean height of 30, each number must be multiplied by 9, giving heights in the ratios 18:27:45 If 4 plants have a mean of 33, their sum is 4*33 = 132 18+27+45=90, so the 4th plant has height 42
July 4, 2016

math
If you mean that the side is 150% as big, then 1.5^2 = 2.25 so, the area increased by a factor of 225% But, if you really mean it increased by 150%, that is, it is now 2.5 times as big, then the area is now 6.25 times as big, so it increased by 525%
July 4, 2016

math
to have perimeter 10, there are only two choices: 1x4 2x3 So, which of those will produce the greater number of rectangles?
July 4, 2016

Math
Sounds like the two circles' centers are on a line parallel with a side of the rectangle. In that case, the diameter of the circles is half the longest dimension of the rectangle. So, two circles of radius 6 can be cut from the paper. Any bigger than that, and they won'...
July 4, 2016

huh?
Hora aderat briligi. Nunc et Slythia Tova Plurima gyrabant gymbolitare vabo; Et Borogovorum mimzebant undique formae, Momiferique omnes exgrabure Rathi.
July 4, 2016

Math
If Akash gave to n people, 180/n + 6 = 180/(n-49) Odd that the amount is not a divisor of 180...
July 4, 2016

Math
that's ok -- we know what a square looks like. Looks like we have (r-8)^2 + (r-9)^2 = r^2
July 4, 2016

physics
NO! 40rad/s ---------------- = 10s 4 rad/s^2 how could you possibly have come up with 40?
July 3, 2016

physics
I assume you mean deceleration, or else it is speeding up. Also, acceleration is measured in rad/s^2. 1200 rpm is 2400π/60 rad/s = 40 rad/s so, if it loses 4 rad/s every second, how long will it take to lose all 40 rad/s?
July 3, 2016

math
30/50 = 60% of the class is absent though, you could say that the 20 present are 66.7% of those absent. Hard to give a good answer when the question is garbled...
July 3, 2016

Calculus
as usual, draw a diagram. If the spider is at height y, then y/15 = tanθ 1/15 dy/dt = sec^2θ dθ/dt when y=5, tanθ = 1/3, so sec^2θ = 1+tan^2θ = 10/9 Now jut plug in your numbers and solve for dθ/dt
July 3, 2016

Calculus
sand falls at the rate of 6 ft/mi^3??? Do you mean 6 ft^3/min ? r = 2h/3, so h = 3r/2 so, when r=2, h=3 v = 1/3 πr^2 h = 1/3 π * (2/3 h)^2 * h = 4/27 πh^3 dv/dt = 4/9 πh^2 dh/dt You know that dv/dt = 6, so 4/9 π * 9 dh/dt = 6 dh/dt = 6/(4π) = 3/(2...
July 3, 2016

Math
3/4 * 4/5 * 1/40 = 3/200 hectare
July 3, 2016

science
the speed drops by 1m/s each second, so a = -1m/s^2
July 2, 2016

math
11.98
July 2, 2016

Math
8-8(8-8) 8^(8*(8-8)) or lots more
July 2, 2016

Math
Hard to say. If she has made 65% of n throws so far, then she needs to throw x more in a row to get to 68%. .65n + x = .68(n+x) .03n = .32x x = 3/32 n
July 2, 2016

Math
(4/7 + 5/21) ------------------- = 17/5 (4/7 - 5/21)
July 2, 2016

arithmetic
well, it is about 1.732 so what do you think? you spent time asking this online when you could have just pushed 2 buttons on your calculator?
July 2, 2016

Physics
g = k/r^2 so, if r doubles, g is cut by a factor of 1/4
July 2, 2016

physics
use the law of cosines to get the magnitude. The diagonals of a parallelogram bisect the angles.
July 2, 2016

Math
1 - 3/8 - 3/10 = 13/40 So, if the original income is x, 13/40 x = 3570
July 2, 2016

Science
10 m/s + 1km/60s
July 2, 2016

Math
OK, let's see whether I can clarify it a bit. If the original fraction is n/d, then we are told: numerator of a fraction is multiplied by 4: change n to 4n denominator is reduced by 2: change d to d-2 4n/(d-2) = 2 Similar changes for the 2nd half, giving us (n+15)/(2d-2...
July 2, 2016

Math
done. see related questions below.
July 2, 2016

Math
clearly not, just as m is not the same as 1/m There is no conversion from °C to "per °C" the 1/°C is part of some other conversion factor, such as thermal expansion: m/°C converts temperature to length.
July 2, 2016

Math
what, you can't wait five minutes?
July 1, 2016

Math
the radius is r = 44/2π = 22/π so, now do the area, πr^2
July 1, 2016

Precalculus
I assume you know how to write sigma: ∑ Note that the numerators go from 3 to 8, alternating signs, and the denominators count down from 8 to 3: 8 ∑ (-1)^k * k/(11-k) k=3
July 1, 2016

Precalculus
n years after 2016, the price will be 12.00 * 1.05^n 12*1.05^14 12*(1.05^14 - 1)/(1.05 - 1) check out your geometric series stuff
July 1, 2016

Math
Now you see why parentheses are important: (x+2)/(4-x) + 1/3 > 1/2 (x+2)/(4-x) > 1/6 If x<4, 6(x+2) > 4-x 6x+12 > 4-x 7x > -8 x > -8/7 So, one solution is the interval (-8/7,4) If x>4, 6(x+2) < 4-x x < -8/7 Not possible, sine we started out with x...
July 1, 2016

physics
245cm^3 ------------ = 21.7s 11.3cm^3/s
July 1, 2016

Chemistry
C2 yields 2CO2 H6 yields 3H2O but that leaves us with 7O, and O only comes in O2 molecules. So, double everything to get 2C2H6 + 7O2 = 4CO2 + 6H2O on the left: 4C 12H 14O on the right: 4C 12H 14O it balances
July 1, 2016

Gupta
x+y = 45 1/x + 1/y = 1/10 the two resistors are 15 and 30 ohms
July 1, 2016

Chemistry
2Bi + (3/2)O2 = Bi2O3 But we don't have 1/2-molecules, so double everything to get 4Bi + 3O2 = 2Bi2O3
July 1, 2016

math
(75*40 - 2.5*1.5)*6 = ?
July 1, 2016

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