Sunday
December 21, 2014

Posts by steve


Total # Posts: 27,663

math
consider the sum 3/5+3/4. round each fraction and estimate the sum. add the two fraction using a common denominator and then round the result. which estimate is closer to the actual answer.
October 27, 2014

math
if the school record for the softball throw is 78 ft about how much farther must Robert throw the ball to match the record. a 15ft b 16ft c 18 ft d 20ft
October 27, 2014

math
4/8-1/4 find the diffence
October 27, 2014

math
3 1/4 + 2 5/6 estimate each sum or difference
October 27, 2014

Algebra
a square has the max area for a given perimeter.
October 27, 2014

math
9/10-3/5 find the difference
October 27, 2014

Stats
you can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html It has very nice input forms so you can specify tails or middle regions.
October 27, 2014

Math
Since v = 1/3 pi r^2 h I get v = (1/3)(3.14)(9)(8) = 75.36 How did you get your answer?
October 27, 2014

physics
A small block of mass m = 225 g is released from rest at point circled A along the horizontal diameter on the inside of a frictionless, hemispherical bowl of radius R = 27.5 cm as shown in the figure below. (a) Calculate the gravitational potential energy of the block-Earth ...
October 27, 2014

Algebra, help please!!!
well, clearly, if you want values between 4.30000000000000... and 4.33333333333333... All you need to do is replace the string of zeroes with something less than 33333333333333... So, you could have 4.3123456789 4.3010101010 4.33333322222 Similarly for the other one
October 27, 2014

algebra. help!
|110-30t| = 40 so, either 110-30t = 40 30t = 70 t = 7/3 = 2.3 or -(110-30t) = 40 -110+30t = 40 30t = 150 t = 5 So, (A) is correct
October 27, 2014

algebra. help!
3x+10 >= 4 3x >= -6 x >= -2 (A) 2.25x >= 180 x >= 80 you are correct
October 27, 2014

Calculus: need clarification to where the #'s go
y = 2√(4x+4) = 4√(x+1) THE DISTANCE D IS FOUND USING d^2 = x^2+y^2 = x^2+16(x+1) = x^2+16x+16 when x=3, d=√73 so, 2d dd/dt = (2x+16) dx/dt d dd/dt = (x+8) dx/dt so, now for the numbers: √73 dd/dt = 11(5) dd/dt = 55/√73
October 27, 2014

Pre-Calc/Trig
it depends. as a function of time, or of distance? wikipedia's article on trajectory has many useful equations.
October 27, 2014

Algebra
(2a-b)^3 = (2a)^3 - 3(2a)^2b + 3(2a)b^2 - b^3 = 8a^3 - 12a^2b + 6ab^2 - b^3 better review your binomial coefficients. I think you used 2 instead of 3. the other is correct
October 27, 2014

Math Homework
3x^2+2x > 2x^2-3 x^2 + 2x + 3 > 0 since the discriminant is negative (4-12), this has no real roots. That is, it does not cross the x-axis. Since f(0) = 3 > 0, f(x) is always > 0, so the solution is all real numbers. 4x^2 - x < 0 x(4x-1) < 0 Recall what you ...
October 27, 2014

algebra
Since the domain of f is all x, the range of f(6x) is the same as the range of f(x). The graph is just contracted horizontally by a factor of 6. The range is unaffected. So, the range of g(x) = f(6x)+1 is just [-11,3]+1 = [-10,4] Things would have been stickier had the domain ...
October 27, 2014

Calculus: need clarification to where the #'s go
just use the formula v = 4/3 pi r^3 a = 4pi r^2, so dv/dt = 4pi r^2 dr/dt = a dr/dt da/dt = 8pi r dr/dt v(14) = 11494 a(14) = 2463 So, we have 80 = 2463 dr/dt da/dt = 8pi(14)(80/2463) = 11.43
October 27, 2014

Algebra
Hmm. I get 2x(3x^2-4xy+2y^2) + 5y(3x^2-4xy+2y^2) = 6x^3 - 8x^2y + 4xy^2 + 15x^2y - 20xy^2 + 10y^3 = 6x^3 + 7x^2y - 16xy^2 + 10y^3
October 27, 2014

algebra--1 question
Just use >= for greater than or equal Your solution is correct. x < -3 or x >= 5
October 27, 2014

algebra 2
He only falls 1500 ft before the chute opens. So, change d to 1500 in the above solution and then rework the numbers.
October 27, 2014

Calculus: need clarification to where the #'s go
you have your formula: pv^1.4 = c, so you get v^1.4 dp/dt + 1.4pv^.4 dv/dt = 0 Now just plug in your numbers: (330^1.4)(-10) + (1.4)(330^.4)(79) dv/dt = 0 -33567.54 + 1125.02 dv/dt = 0 dv/dt = +29.84
October 27, 2014

Calculus
To find the rate of increase, note that the distance x after t hours is given by x^2 = (50+19t)^2 + (24t)^2 At 3 pm, t=3, and we have x^2 = 117^2 + 72^2 = 16633 x = 137.4 Now we have to find the derivative: 2x dx/dt = 38(50+19t)+48(24t) = 1874t + 1900 So, at t=3, we have 2(137...
October 27, 2014

science-gen chem
.969g CaCl2 = 0.00873 moles 1.111g KIO3 = 0.00519 moles Each mole of CaCl2 requires 2 moles of KIO3, so clearly the KIO3 is the limiting reagent. So, since each mole of KIO3 produces 1/2 mole of Ca(IO3)2, we get 0.00269 moles of Ca(IO3)2 = 1.051g
October 27, 2014

Calculus - PLEASE HELP!
3√(x^2+y^2) * (x + yy') = (x+yy')/√(x^2+y^2) + 1 x+yy'(3√(x^2+y^2) - 1/√(x^2+y^2) = 1 y' = (1/(3√(x^2+y^2) - 1/√(x^2+y^2) - x)/y y' = [x+√(x^2+y^2) - 3x(x^2+y^2)]/(y(3(x^2+y^2)-1)) So, we want either the numerator ...
October 27, 2014

Calculus
draw a diagram. Let the distance from the pole be x, and the shadow's length be s. Using similar triangles, we have s/6 = (x+s)/15 or, 5s = 2x+2s 3s = 2x so, ds/dt = 2/3 dx/dt plug and chug
October 27, 2014

Calculus
16/(x^2+16)^(3/2)
October 27, 2014

Calculus
dv/dt = 4pi r^2 dr/dt plug and chug
October 27, 2014

Calculus
using implicit derivatives, (x+2y)y'=2x-y (1+2y')y' + (x+2y)y" = 2-y' Now plug in the numbers: y'(3) = 2, so (1+4)(2) + (3)y" = 2-2 10+3y" = 0 y" = -10/3
October 27, 2014

Math
Now, if you meant x^2-31x+108 = 0 then (x-4)(x-27) = 0 x^x is a bit nastier
October 27, 2014

Calculus
df/dx = df/dg * dg/dx = g/√(g^2-4) * (3) = 3(3x-2)/√((3x-2)^2-4) = 3(3x-2)/√(9x^2-12x) at x=3, that's 3(7)/√45 = 21 / 3√5 = 7/√5
October 27, 2014

math
Since when do Alonso and Italian chicken sound Chinese? and that's "whoever deciphers this." The phrase acts as the object of the preposition, not just "who".
October 27, 2014

Calculus
from you formula for v, dv/dt = 4pi r^2 dr/dt now plug in the numbers.
October 26, 2014

Calculus
I think you have a typo. I'm sure you meant y = 2sinx + (sinx)^2 since y(π/6) = 2(1/2) + 1/4 = 5/4 So, y' = 2cosx + 2 sinx cosx at x=π/6, y' = 2(√3/2) + 2(1/2)(√3/2) = √3 + √3/2 = 3√3/2 Now you have a point and a slope. Dig ...
October 26, 2014

Fractions
Starting with x peaches, a = x-(x/2 + 1/2) b = a - (a/3 + 1/3) c = b - (b/4 + 3/4) c - (c/5 + 1/5) = 19 now start substituting in and you wind up with x = 101
October 26, 2014

Calculus
f'(x) = -4x-2 f'(-1) = 2 point-slope form: y+2 = 2(x+1)
October 26, 2014

Calculas
y = secx y = (cosx)^-1 y' = -1 (cosx)^-2 (-sinx) = sinx/cos^2x = secx tanx similarly for tanx, using the quotient rule
October 26, 2014

calculus
a square has minimum perimeter for a given area
October 26, 2014

Algebra
it's easiest to use the polar form if z = r cisθ z^2 = r^2 cis2θ so, r^2 cis2θ = 2 cis π/2 r = ±√2 θ = π/4 So, we have √2 cis π/4 -√2 cis π/4 √2/√2 + √2/√2 i = 1+i or -(1+i) check: (1+...
October 26, 2014

Algebra
That vertical asymptote at x = -1 means the range is (-∞,∞)
October 26, 2014

Algebra
for the root, we need x >= 0, or [0,∞) but, the denominator cannot be zero, so the domain is (0,∞)
October 26, 2014

algebra
we want f(2), so that means we need √(x+1) = 2 so, x=3 f(2) = 1/3
October 26, 2014

Algebra
well, where are the denominators zero? x-64 = 0 x^2-64 = (x-8)(x+8) = 0 x^3-64 = (x-4)(x^2+4x+16) = 0
October 26, 2014

Calculus
df/dx = 6(2x+1)^2 so, g' = 1/f' g'(1) = 1/(6*9) = 1/54 check: g(x) = (∛x-1)/2 g'(x) = 1/(6(∛x^2)) g'(1) = 1/(6*9) = 1/54
October 26, 2014

Calculus 1
f'(x) = -3/x e^(1-x^2) (2x^2 lnx - 1) f(1) = 0 f'(1) = -3(1)(-1) = 3 So, now you have a point (1,0) and a slope (3) and the line is y-0 = 3(x-1)
October 26, 2014

calculus
Wow. This one gets tricky, since we're dealing in 3D, rather than the usual 2D. If the bottom of the pole is at B, and the top is at T, and the point directly across the road is at Q, then if the man is x from Q, the diagonal distance across the road (BQ) is y, then y^2 = ...
October 26, 2014

calculus
y = 9√x y(16) = 36 y(25) = 45 So, the secant has slope (45-36)/(25-16) = 1 So, now use the point-slope form to get the equation for a line with slope 1 through (16,36) For the tangent line, the slope y' = 4.5/√x is 9/8 at x=16 Again, use the point-slope form to...
October 26, 2014

Calculus 1
If the hypotenuse has length z, then h^2+36 = z^2 when h=8, z=10 2h dh/dt = 2z dz/dt or, h dh/dt = z dz/dt So, when h=8, 8*2 = 10 dz/dt dz/dt = 1.6 m/s
October 26, 2014

Algebra
GanonTEK is correct. If you don't have ready access to a graphing utility, just use what you know about parabolas. Since this is one which opens downward, it is positive between the roots, where it crosses the x-axis.
October 26, 2014

precalculus
If the cuts are at a distance of x from the center, then since the area of a circular segment is a = 1/2 r^2(θ-sinθ) we want that to be 1/3 of the area, or π/3 r^2 So, 1/2 r^2(θ-sinθ) = π/3 r^2 3(θ-sinθ) = 2π Solve that using your ...
October 26, 2014

Geometry
You have to tell us what angles 1 and 2 are, in terms of the points A,B,C,D.
October 26, 2014

Algebra
since the domain of √u is u>=0, we need 2-x >= 0 That is, x <= 2 Next, we also need 1-√(2-x) >= 0, so √(2-x) <= 1 2-x <= 1 means x >= 1 -(2-x) <= 1 means x <= 3 So, we have a final domain of 1 <= x <= 2 The graph is at http://...
October 26, 2014

Algebra
the denominator cannot be zero. So, x^2+bx+8 must have no real roots. For that to happen, we need the discriminant to be negative: b^2-32 < 0 So |b| <= √32 5 is the greatest integer less than √32
October 26, 2014

science (Need FAST FEEDBACK!!!)
No idea. I'd have to google the terms. Oh, wait, you could have done that just as easily as asking here and waiting for a response.
October 26, 2014

Math algebra
for any radius r, the circumference C is C = 2πr So, just plug in the numbers you have for r
October 26, 2014

math
(4+x)(8+x) = 4*8 + 64 x^2+12x-64 = 0 (x-4)(x+16) = 0 x = 4 So, the rectangle is 8x12 with area 96 (32+64)
October 26, 2014

MATHS
If there were x 50-cent coins, x/6912 = 7/16 x = 3024 So, they collected 6912*.25 + 3024*.50 = $3240.00
October 26, 2014

Calculus
a square encloses the maximum area for a given perimeter.
October 26, 2014

second degree equation word problem
If there are now x rows, then each row has 720/x seats. The new configuration means that (x-4)(720/x + 6) = 720 (x-4)(6x+720) = 720x (x-4)(x+120) = 120x x^2-4x-480 = 0 (x+20)(x-24) = 0 ...
October 25, 2014

Pre-calc
cos(-7pi/6) = cos(7pi/6) = cos(pi+pi/6) = -cos(pi/6)
October 25, 2014

math
See http://www.wolframalpha.com/input/?i=f%3E%3D4 There's a number-line plot there.
October 25, 2014

Precalculus
using the law of cosines, the ship's distance x from the port is x^2 = 170^2 + 90^2 - 2*170*90 cos 14° Now just figure the coordinates of the ship and port to get the desired course. That assumes that there are no cross currents for the rest of the trip.
October 25, 2014

Precalculus
Hmm. Not having the diagram is a bit of a problem. In my diagram, extend the sea-level line TR to intersect PS at Q. Then, I have the angle of depression α = ∠PTR and β = ∠PQR. Apparently that is wrong, so please describe the diagram using only labeled ...
October 25, 2014

Precalculus
I don't see how ∠SPT can be 99°. ∠SPT = ∠SPR + ∠RPT = 51°+69° = 120° Did I miss something in the explanation?
October 25, 2014

Pre-Calc/Trig
you want two factors of 24 which add up to 10. List the factors: 1 2 3 4 6 8 12 24 Take them in pairs, working in from the ends. Note that 4 and 6 add up to 10, so you have (x+4)(x+6) = 0 x = -4 or -6
October 25, 2014

Precalculus
That is the angle between the vectors (7,10,0) and (7,0,3) So since (7,10,0)•(7,0,3) = √149√58 cosθ, cosθ = 49/√8642 = 0.527
October 25, 2014

math
f is increasing where f' is positive f' = 4-3x^2 So, where is 4-3x^2 > 0? similarly for decreasing. max/min where 4-3x^2 = 0
October 25, 2014

math
f' = (x+3) / 4x^(7/4) f' = 0 when x = -3. what about x=0?
October 25, 2014

Math
b = 3j m = 4(b+j) m = 4b+4j m = 4b+4(b/3) m = 16/3 b yes 3 = 1+2 3*8 = (1+2)*8 = 8+16 = 24 (12-4)*(2+1) = 8*3 = 24 12-4*2+1 = 12-8+1 = 5 in the absence of parens, multiplication is done before addition. That's why 3x+2 is (3*x)+2 and not 3*(x+2)
October 25, 2014

math
3*5 = 1/3 * x
October 25, 2014

Algebra
AB has slope 2/-6 = -1/3 So, (y+2)/(6-x) = -1/3 3y+6 = x-6 x=3y+12 So, pick any y and that will give you an x.
October 25, 2014

Calc
since v = 4/3 pi r^3 and a = 4 pi r^2, v = 1/3 ar so, dv/dt = 4pi r^2 dr/dt = a dr/dt so, dr/dt = (dv/dt)/a dv/dt = 1/3 (r da/dt + a dr/dt) = 1/3 (r da/dt + a*(dv/dt)/a) = 1/3 (r da/dt + dv/dt) = 1/2 r da/dt So, 10 = 1/2 (6.5) da/dt da/dt = 3.077 cm^2/s
October 25, 2014

Maty
3d+300m = 111 5d+600m = 198 Now just solve for d and m
October 25, 2014

algebra
check the related questions below
October 25, 2014

Chemistry
11.9g of am carb = 11.9/96.1 = 0.124 moles So, you get 0.248 moles of NH3 0.124 moles CO2 0.124 moles H2O Total moles of gas: 0.496 So, since 1 mole makes 22.4L at STP, adjust for your conditions.
October 25, 2014

college algebra
Using the point-slope form of the line, y-39000 = (64/39)(x-2000) So, when is y > 61000?
October 25, 2014

Physics
a = (36.6 m/s)/(8.22 s) = 4.45 m/s^2 F = ma
October 24, 2014

Calc
who cares about the volume? A = πd^2 dA/dt = 2πd dd/dt Now plug in your numbers to find dd/dt
October 24, 2014

Secondary Math
Hmmm. You have TR(-15x+3) = (-15x+3)(-2x+6) So, TopRight = -2x+6 BC = -3(-5x+1) = 15x-3 So, BottomCenter = 15x-3 That means BottomLeft = 2x-6 TopLeft = (-2x+6)/-3 = 2/3 x - 2 So, the filled-in square is (2/3 x - 2) (-3)(-2x+6) (3)(-5x+1)(-15x+3) (2x-6)(15x-3)(30x^2-96x+18)
October 24, 2014

Algebra
if the domain is all real numbers then the denominator can never be zero. That means it has no real roots. Thus, the discriminant is negative: b^2-32 < 0 So, if 0<=b<=5 x^2+bx+8 is never zero
October 24, 2014

Physic
a = 320km/hr / 6.5s * 1000m/1km * 1hr/3600s = 13.68 m/s^2 Since F = ma, the net force is 13.68m Since the net force is 1.52*10^4-5.2*10^3, divide that by a to get m.
October 24, 2014

MATH HELP asap PLEASE
the vectors to add are v = (550cos7°,550sin7°)+(85cos20°,85sin20°) so, plug in the numbers and get the sum. Then just get |v| and its direction
October 24, 2014

math
.4(6) = 2.4 = 24/10 = 12/5 or, .4 = 2/5, so .4(6) = (2/5)(6) = 12/5
October 24, 2014

Math
correct Though, to save us having to search back for your previous postings, it's better just to add a reply to them yourself. You can see where lots of posts have several replies.
October 24, 2014

Algebra
the denominator cannot be zero. So, its discriminant must be negative. That means 1-4c < 0
October 24, 2014

Math
Unfold the prism into a sheet, and draw a line from one point to the other. Then fold it back up again.
October 24, 2014

math
After Amy, .85 remained. After Beth, .80*.85 = .68 remained After Cathy, .88*.68 = .5984 remained So, 59.84% of the job remained undone. So, how did you arrive at 53%/ It's always good to show your work, so we can check to be sure your logic is correct.
October 24, 2014

Algebra
at x=1, r is undefined (∞) As x gets huge, r-> 0 The denominator is always positive, So, the range is (0,∞) See the graph at http://www.wolframalpha.com/input/?i=1%2F%281-x%29^2
October 24, 2014

Calc
A = πd^2 dA/dt = 2πd dd/dt Now plug in your numbers and solve for dd/dt
October 24, 2014

algebra
we want 23 + 1.75x < 7 + 3x Now just solve for x
October 24, 2014

algebra
that would be x miles, where 45.00+0.25x = 35.00+0.30x Now just solve for x
October 24, 2014

Trig calc
x = r cosθ y = r sinθ Now just plug in your numbers
October 24, 2014

Trig
x = r cosθ y = r sinθ Now just plug in your numbers
October 24, 2014

Math Calc
for any x, sin(x+180) = -sin(x) check the sum formula for sines
October 24, 2014

Math
f(-x) = -x^3+x^2+10x-24 2 sign changes, mean either 2 or 0 negative roots "A few" is not a very precise answer.
October 24, 2014

Math
1 sign change, so there is exactly 1 positive real root. The sign change is from +x^2 to -10x
October 24, 2014

algebra
2f-21 looks good to me. 2f is two times 2f-21 is 21 less than that. good work.
October 24, 2014

math
10+30*2.5
October 24, 2014

Math Trig
h/(120*3) = tan 40 now just evaluate
October 24, 2014

Algebra
we need |500m - 200t| <= 5 where m and t are the rates in $/minute
October 24, 2014

Pages: <<Prev | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | Next>>

Search
Members