Wednesday
May 25, 2016

Posts by Steve

Total # Posts: 40,816

math
sounds like a rectangle to me.
May 9, 2016

Science
the same
May 9, 2016

calculus
(lnx)/(x) x^(lnx-1) = x^(lnx)/x
May 9, 2016

calculus
Is the lnx/x suppose to be (lnx)/(x) or ln(x/x)?
May 9, 2016

calculus
I don't understand how you went from y' = lnx x^(lnx -1) + lnx x^lnx (1/x) to lnx/x x^lnx + lnx/x x^lnx. Where did the -1 go? May you please explain?
May 9, 2016

calculus
recall that d/dx x^n = n x^(n-1) d/dx a^x = lna a^x so, if y = u^v, y' = v u^(v-1) u' + lnu u^v v' Here you have u = x v = lnx So, y = x^lnx y' = lnx x^(lnx -1) + lnx x^lnx (1/x) = lnx/x x^lnx + lnx/x x^lnx = 2lnx/x x^lnx or, do it like this y = x^lnx lny = lnx...
May 9, 2016

calculus
Find dy/dx. y = x^ln x, x > 0
May 9, 2016

Math
well, geez - did you plug in the values? y(0) = 5, so it will end in +5 1^2 = 1, so y = -x^2 + 5 so, yes, B is the answer.
May 9, 2016

Algebra
y = kxz 4 = k*4*1 k = 1 y = xz
May 9, 2016

Algebra
If the point is x miles from NYC, then since time = distance/speed, (3458-x)/(850+50) = x/(850-50)
May 9, 2016

math
Assuming you actually replace the 1st ball before drawing the 2nd, then the chance of drawing a green ball in at least one of the draws is the complement of drawing no green ball either time. The chance of no green ball twice in a row is 50/70 * 50/70 = 35/49 So, the chance of...
May 9, 2016

Differentiation
again?
May 9, 2016

maths
2(70 + 80+20) - 2(70+80) = 2(20) = 40 m or, 20m on each long side...
May 9, 2016

Differentiation
A = 3t^2 + 7 dA/dt = 6t now plug in t=5
May 9, 2016

Math
q = d+8 n = d-5
May 9, 2016

Algebra
Since time = distance/speed, 66/(r+7) = 24/r
May 9, 2016

math
1 + 6/16 = 1 + 3/8 = 1 3/8 can't see how that would have caused you any trouble...
May 9, 2016

physics
mv1 = <0,-144> mv2 = <-270/√2, 270/√2> add the vectors and then change back to direction and magnitude.
May 9, 2016

functions
A little division shows that 6x^3-ax^2+bx+c / (x+4) has a remainder of -16a-4b+c-384 6x^3-ax^2+bx+c/(x^2-4) has a remainder of (b+24)x+c-4a So, -16a-4b+c-384 = -220 b+24 = 23 c-4a = -26 solve those and you get f(x) = 6x^3 + 31/2 x^2 - x - 88 You can verify the remainders for ...
May 9, 2016

MATHEMATICS
geez, impatient much?
May 9, 2016

MATH
Draw a diagram. The distance x between the tree and pole can be found using 10.65/x = tan60° Then the remaining height y of the top of the tree and the top of the pole is found by y/x = tan46°
May 9, 2016

math
set it up in the usual way x^2-x+2 = 0 b^2-4ac = 1-8 = -7 so, what does a negative discriminant tell you?
May 9, 2016

Geometry
could be, depending on where the docks are. The docks could be anywhere from 0 to 40 yards apart.
May 9, 2016

algebra
good as far as you went, but 10/√27 10/(3√3)
May 9, 2016

math
sinA = 2 sinA/2 cos A/2 similarly for B and C Now add them up.
May 9, 2016

math,science
a = -22m/s / 13s = -22/13 m/s^2
May 9, 2016

geometry
you can easily see that the region is a rectangle. Rotate a rectangle around one of its sides and you get a cylinder. Then it's easy. See my work at http://www.jiskha.com/display.cgi?id=1462581546
May 9, 2016

math
This may help: http://mathforlove.com/2012/02/midpoints-of-a-quadrilateral-form-a-parallelogram/
May 9, 2016

math
the interest is the same for each year: 13000 * 0.08 clearly you need to review why the "normal" method works as it does.
May 9, 2016

Algebra II
well, π radians = 180°
May 9, 2016

Algebra II
use the law of sines
May 9, 2016

geometry
If they have the same base area, then the volumes are in the ratio of the heights, cubed. That is 250/2 = (H/h)^3
May 9, 2016

Algebra II
did you draw a diagram? If so, you can see that the distance x is found using the law of cosines: x^2 = 3.6^2 + 2.3^2 - 2*3.6*2.3*cos66˚
May 9, 2016

math
There are 20 greens in 70 gumballs The chance of drawing zero green ones is 50/70 * 49/69
May 9, 2016

math
the two terms are 9d apart. So, d = -2 Now you have d, and can easily find a, so S15 = 15/2 (2a + 14d)
May 9, 2016

math
huh?
May 9, 2016

Trigonometry
the height in feet can be found using h/5280 = tan6°
May 8, 2016

Geometry
V = 18*w*12 where the width is w.
May 8, 2016

math: pre-calculus
by definition, e^(ln x) = x ln(e^x) = x ln and e^ are inverse functions, just like x^2 and √x Assuming no typos, I see ln(e^3y)+ln(ey)-ln(e^4) = ln(e^3y * ey / e^4) = ln(y^2) = 2ln(y)
May 8, 2016

math: pre-calculus
you want p = a e^(kt) clearly p(0) = 53 p = 53 e^(kt) p(3) = 90, so 53 e^(3k) = 90 e^(3k) = 90/53 3k = ln(90/53) k = ln(90/53)/3 = 0.1765 so, we have p(t) = 53 e^(.1765t) Now you try the others, lest you be accused of homework dumping...
May 8, 2016

geometry (please help)
The area of the triangular base is (1/2)(9)(10) = 45 There are two of those, for a total of 90 There are three rectangular faces of area 9*10+9*9+9*13.5, for a total of 292.5 Total area is thus 90+292.5 = 382.5 in^2
May 8, 2016

math: pre-calculus
note that this is just log(x) shifted left 3 and down 8. So, now you can relate its properties to those of h(x)
May 8, 2016

math
just plug in the data and solve for w. Then you can get the length. w(3w-2) = 65 Of course, it also helps to know that 5*13 = 65 ... just sayin'
May 8, 2016

algerbra
since distance/speed = time, (1600/400) + (1600/320) = ?
May 8, 2016

Math Algebra
since distance/speed = time, 200/(x+3) = 200/(x-3) - 1
May 8, 2016

math
290-50 = 240 240/60 = 4 so, in 4 more hours
May 8, 2016

Calculus
V(0) = 500,000 V(5) = 405,000 (V(5)-V(0))/(5-0) = -19,000 ft^3/min
May 8, 2016

math , steve or damon pls
right on both of them.
May 8, 2016

math
pi, not pie! 2pi(r^2+rh) = 2pi(25+75) = 200pi Now just multiply that are by the cost, which is .0450/cm^2
May 8, 2016

calculus
let u = 2x you know lim sin(u)/u, right?
May 8, 2016

damonnnn math help
since multiplication is commutative, 6t^3 * 6t^3 = 6*6 * t^3*t^3 = 36t^6 t^3*t^3 = t*t*t * t*t*t = t^6, not t^9 add exponents when multiplying powers
May 8, 2016

Geometric series
a = -1 r = 3 Sn = (-1)(3^n-1)/(3-1) = (1-3^n)/2 = -3280 1-3^n = -6560 3^n = 6561 n = 8
May 8, 2016

calculus
what, you forgot your Algebra I? (x+1/x)^2 = x^2 + 2 + 1/x^2 Surely you can handle each of those terms...
May 8, 2016

math
figure the volume in ft^3, then multiply by how many gal/ft^3. That will give you how many gallons will fit. I have no idea how many gallons are actually in the tank...
May 8, 2016

calculas
let the distance from 3rd base be x. Then the distance z from home is z^2 = 90^2 + x^2 so, to find dz/dt, 2z dz/dt = 2x dx/dt So, find z when x=20, then plug in dx/dt and x.
May 8, 2016

Maths - eh?
If B is a point, how can a line be perpendicular to it?
May 8, 2016

mathematics-permutation and combination
The two boys are separated by 10 others on each side, right? Now you can easily figure the solution.
May 8, 2016

math
Just draw a diagram. All those right angles help a lot. XZ/2800 = tan(90-63)° 2800/XP = cos(90-25)°
May 8, 2016

math
x/180 = cot 27°
May 8, 2016

Trigonometry and Right Triangles!
the sides are in the ratio 1:√3:2 so if the hypotenuse is 16, then the sides are 8,8√3,16 and the perimeter is 24+8√3
May 8, 2016

Math
2x+5x = 4.27 x = .61 So, they have 1.22 and 3.05 lbs. Now you can decide how much has to be given so they have the same amount.
May 8, 2016

math
180/x = tan 27°
May 8, 2016

math
with A at (0,0) we just add the x- and y-displacements to get the final location: <4,0>+<0,-3>+<-3.06,-2.57> = <0.94,-5.57> Now you can find the distance and bearing.
May 8, 2016

Maths
x+y=120 0.9x + 1.2y = 120 80+40 = 120 72+48 = 120
May 8, 2016

Math
If the diamond is just a rotated square, then its diagonal is 3, so its area is 9/2. So, the rectangle has width 3 and area 27, so its height is 9.
May 8, 2016

math
Draw a diagram. It will be clear that using the law of cosines, the distance d is found using d^2 = 300^2 + 200^2 - 2*300*200 cos33°
May 7, 2016

MATH
1/14 (196x+17-10)= (14/20)(20x+12x) has no solution since (14/20)(20x+12x) = 14x + 42/5 and 1/14 (196x+17-10) = 14x + 1/2 and there is no value of x such that 14x+42/5 = 14x + 1/2
May 7, 2016

MATH
The equation 1/14 (196x+17-10)=______ (20x+12x) has no solution. The equation (4x+24/122)=_____ (x+16/122)
May 7, 2016

MATH!
not sure what question is answered by the 4, but you are correct in assuming that the equation is an identity.
May 7, 2016

MATH!
The equation 1/14 (196x+17-10)=______ (20x+12x) has no solution. The equation (4x+24/122)=_____ (x+16/122) Im sure the answer for the second one is 4, (4x+24/122) = 4 (x+6/122)
May 7, 2016

math
The answer is as follows: 9-3÷1/3+1 9-3*3/1+1 9-9+1 0+1 Answer = 1
May 7, 2016

math
other interpretations of 9 minus 3 divided by 1/3 plus 1 are (9-3)/(1/3) + 1 = 6*3+1 = 19 (9-3)/(1/3 + 1) = 6/(4/3) = 9/2 9 - 3/(1/3) + 1 = 9-9+1 = 1 9 - 3/(1/3 + 1) = 9 - 9/4 = 27/4 As you can see, using math symbols is a lot less ambiguous than just words, and grouping ...
May 7, 2016

math
you have correctly factored the left side. What has that to do with the right side? Or is that 16/22 a typo?
May 7, 2016

math
The equation 1/14 (196x+17-10)=______ (20x+12x) has no solution. The equation (4x+24/122)=_____ (x+16/122) Im sure the answer for the second one is 4, (4x+24/122) = 4 (x+6/122)
May 7, 2016

math
The equation 1/14 (196x+17-10)=______ (20x+12x) has no solution. The equation (4x+24/122)=_____ (x+16/122) Im sure the answer for the second one is 4, (4x+24/122) = 4 (x+16/122)
May 7, 2016

math
R = R1 + R2 = 10 + 15 = 25Ω
May 7, 2016

math
clearly a permutations problem, since the order of award matters. So, there are 50P3 ways to arrange the selections.
May 7, 2016

math
the desired point will be the center of the circle passing through the three points. So, if that is (h,k), we have (x-1)^2 + (y-1)^2 = r^2 (x-7)^2 + (y-1)^2 = r^2 (x-1)^2 + (y-9)^2 = r^2 Now, you can solve those to find (h,k) and r, or you can note that the three points form a...
May 7, 2016

calculas 1
f(0) = 0 f(9) = 9^9 (wow!) (f(9)-f(0))/9 = 9^8 f'(x) = 9x^8 so, you want c such that f'(c) = 9^8 9c^8 = 9^8 c^8 = 9^7 c = 9^(7/8) ≈ 6.84 ∊ [0,9]
May 7, 2016

math
The equation 1/14 (196x+17-10)=______ (20x+12x) has no solution. The equation (4x+24/122)=_____ (x+16/122) Im sure the answer for the second one is 4, (4x+24/122) = 4 (x+16/122)
May 7, 2016

math
if f(x) = x^2+bx+c, we have (x^2+bx+c) + (x^2-bx+c) = 2x^2 2x^2+c = 2x^2 so, c=0 and f(x) = x^2+bx f(2016) = 0, so 2016^2 + 2016b = 0 b = -2016 f(x) = x^2 - 2016x = x(2016-x) f(10) = 10(2016-10) = 10(2006) = 20060
May 7, 2016

trig
not quite sure what "double angle of tan" means, but if you want tan(u) where u is in QI and sec(u) = 7/2, then draw the triangle. clearly tan(u) = √45/2 = 3√5/2. So, tan(2u) = 2tan(u)/(1-tan^2(u)) = 2(3√5/2)/(1-45/4) = -12√5/41
May 7, 2016

maths-factor
1/(x-3) < -1 what do you mean factors? You want a solution set If x-3 > 0, then 1 < 3-x x < 2 Not possible if x>3 If x-3 < 0 or x < 3, then 1 > 3-x x > 2 So, the only solutions are 2<x<3 verify here: http://www.wolframalpha.com/input/?i=1%2F%...
May 7, 2016

geometry
the distance from (-6,-8) to (0,0) is 10. So, (x+6)^2 + (y+8)^2 = 10^2
May 7, 2016

geometry
Write the standard equation for the circle center (-6,-8), that passes through (0,0). I know that the formula would leave the 1qstr part as (x+6)+(y+8) I'm not sure about the radius when it goes through (0,0)
May 7, 2016

integral calculus
no idea what box you're talking about. Probably an integral sign which does not render in your font. Judging from the answer produced by wolframalpha.com http://www.wolframalpha.com/input/?i=integral+dx%2F%283x^3-5%29^3 you have some major tricks to use.
May 7, 2016

algebra
the max height is where t = -b/2a = 3 h(3) = 256 ft h=0 when t=7
May 7, 2016

calculas 1
You give no limits on the area.
May 7, 2016

calculas
clearly the rectangles are bounded at x = 0, π/6, π/3, π/2, 2π/3, 5π/6, π So, evaluate g(x) at the boundaries and add up the areas. What do you get? There are plenty of online calculators for this to check your work.
May 7, 2016

calculas 1
Have you tried laying out a few rows? I'm sure you will see a pattern. You will be adding up sequences of even or odd numbers...
May 7, 2016

Geometry
Since s=rθ, the circumference of the base of the cone is 15 * 4π/3 = 20π So, the radius of the base of the cone is 10. Now you can find the height of the cone, and thus the volume.
May 7, 2016

math
recall that x = vcosθ t y = vsinθ t - g/2 t^2 dy/dx = dy/dt / dx/dt = (vcosθ - gt)/(-vsinθ) -cotθ + g/(vsinθ) t we want dy/dx = tan(θ/2) = (1-cosθ)/sinθ = 1 - cotθ -cotθ + g/(vsinθ) t = 1 - cotθ t = vsinθ/g
May 7, 2016

math
just use your equation of motion, and find when its slope (derivative) is tan(alpha/2).
May 7, 2016

Trig
If we call the lengths OA and OB x and y, then we have, using the law of cosines, x^2+y^2-√3 xy = 1 That is just an ellipse with its extreme values at x=2 or y=2. So, the maximum value of OB is 2.
May 7, 2016

Calculus
well, the two curves intersect at (±√(10/3),40/3), so the area is 2*integral[0,√(10/3)] (x^2+10)-(4x^2) dx = (40/3)√(10/3)
May 6, 2016

Calculus
work = force * distance, so ∫[0,25] 30-.1x dx
May 6, 2016

Math
Come on, man. The area is just a 6x4 rectangle. Rotating it around the y-axis jives you a cylinder with r=6 and h=4, so its volume is 144π Or, if you must use calculus, v = ∫[0,6] 2πx*4 dx = 144π Or, using the Theorem of Pappus, it is the area of the ...
May 6, 2016

math
yes it is
May 6, 2016

Math Help Please
anything that ends in .9... is an integer. So, 0.999999... = 1 1.999999... = 2 4.999999... = 5 and so on
May 6, 2016

Programming
Oops. I dislayed the total, not the average. Change that to avg /= n Display "The average score for Student #",s," is ",avg
May 6, 2016

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