Friday
May 27, 2016

Posts by steve

Total # Posts: 40,845

math
4! = 24
April 24, 2016

Maths
words, words, words. This is math, so use math 4x^2-5x+7 terms are separated by + and - signs, so there are three terms
April 24, 2016

math(counting)
if all you want is permutations of the letters, MAIRE: 5! = 120 OISEAU: 6! = 720 If you want your anagrams to be actual words, then of course there will be a lot fewer. Better get a good French dictionary.
April 24, 2016

math(counting)
what does "near" mean? There are only 5 kids, after all.
April 24, 2016

Math
If she started out with x, and was left with 15 more than half of what she started with, then x - x/8 - x/5 - x/10 = x/2 + 15 x = 200
April 24, 2016

Ic
I assume you can handle the java syntax, but the flow of logic is integer a,b,c,option,err print "Enter two integers: " read a,b print "Enter option: 1: add 2: subtract 3: multiply 4: divide " read option err=0 case option { 1: c=a+b 2: c=a-b 3: c=a*b 4: if...
April 24, 2016

math
233489
April 24, 2016

precalc
oops. tanϕ = -1/√15 tan(θ+ϕ) = (√8 - 1/√15)/(1-(√8)(-1/√15)) = (32√2 - 9√15)/7 = 1.48
April 24, 2016

precalc
cos(θ) = −1/3 QIII, so tanθ = √8 sin(ϕ) = 1/4 in QII, so tanϕ = -√15/4 tan(θ+ϕ) = (tanθ + tanϕ)/(1-tanθ tanϕ) = (√8 - √15/4)/(1-(√8)(-√15/4)) = (18√15 - 31√2)/52
April 24, 2016

Absolute and relative change
6%
April 23, 2016

Precal/Math
log(3-2x)-log(x+24)=0 log (3-2x)/(x+24) = 0 (3-2x)/(x+24) = 1 3-2x = x+24 x = -7
April 23, 2016

geometry
Thye area of a regular hexagon is 38 cm^2. What is the area of a regular hexagon with sides 4 times as long?
April 23, 2016

Calculus!!
dy/dx = xy/2 dy/y = x/2 dx ln y = 1/4 x^2 + c y = c e^(x^2/4)
April 23, 2016

AP Calculus
A yes, if f"=0 and f'≠0 B find g'(0) Then the tangent line is y-5 = g'(0) (x-0)
April 23, 2016

Calculus
The large cylinder has a cross-section 4 times that of the smaller one, so its water level rises 1/4 as fast as it falls in the smaller one.
April 23, 2016

Calculus
A a = ∫[0,5] 3/e^x dx = 3 - 3/e^5 B now you want c such that ∫[0,c] 3/e^x dx = ∫[c,5] 3/e^x dx 3 - 3/e^c = 3/e^c - 3/e^5 6/e^c = 3 + 3/e^5 e^c = 2/(1+e^-5) c = ln 2/(1+e^-5) C each semicircle has diameter equal to y. Adding up all those thin slices of ...
April 23, 2016

math
not sure what H= 10 inches from measuring the perimeter of the base is 2 inches means
April 23, 2016

AP Calculus
A (1+x)y^3 + (x^4)y - 85 = 0 y^3 + 3(1+x)y^2y' + 4x^3y + x^4y' = 0 y' = -(y^3+4x^3y)/(3(1+x)+x^4) = -(y^3+4x^3y)/(x^4+3x+3) B y'(3) = -109/93 So, the tangent line is y-1 = -109/93 (x-3) C y(3) = 1, so g(1) = 3 g'(1) = 1/y'(3) = -93/109
April 23, 2016

GEOMETRY HELP PLEASE
well, maybe not. It just might mean that AB is shorter than CD. In that case, h = 3√5 and x = -2, so CD=8 and AB=4, making the area (8+4)/2 (3√5) = 18√5
April 23, 2016

GEOMETRY HELP PLEASE
Drop altitudes CE and DF The trapezoid now can be seen to be rectangle CDEF and two right triangles of height h and base x. h^2+x^2 = 7^2 h^2 + (8+x)^2 = 9^2 Hmmm. I get x = -2 I guess I have drawn the figure incorrectly. Maybe you can use my ideas in your own drawing.
April 23, 2016

math
L = K∛M 15 = K∛125 15 = K*5 3 = K
April 23, 2016

converting parabolic equations
x = 8(y-1)^2-15 x = 8(y^2-2y+1)-15 x = 8y^2-16y-7
April 23, 2016

physics
So, if their ratio is 1.1, you have determined that Ve/Vb = 1.1 since distance = speed * time 3*10^-9 Ve = 1.1*3*10^-9 Vb = 3.3*10^9 Vb So, De-Db = 0.3*10^-9 Vb
April 23, 2016

Calculus
c'mon, you can do this. dm/dt = -0.22m dm/m = -0.22 dt ln(m) = -0.22t + c m = c e^(-0.22t) c is the initial amount, so m(t) = 20 e^(-0.22t) I'm sure you can find the half-life now, ok?
April 23, 2016

Calculus
we know the slope is dy/dx, so at (1,2), the slope is -3. The tangent line is thus y-2 = -3(x-1) y dy = -6x^2 dx 1/2 y^2 = -2x^3 + c y = √2 √(c-2x^3) you know that the domain of √ is non-negative numbers, so c-2x^3 >= 0 2x^3 <= c x <= ∛(c/2)
April 23, 2016

Calculus
recall that for parametric curves, the curvature is x'y" - x"y' ----------------- (x'^2 + y'^2)^(3/2) so, for your function, that is x' = 2t x" = 2 y' = 2t^2 y" = 4t (2t)(4t)-(2)(2t^2) ----------------------- = 4t^2/(8t^3(1+t^2)) = 1...
April 23, 2016

Pre-Calc
the domain of log(u) is u>0, regardless of the base of the logs. So, you need 3x-8 >0 x > 8/3 or, (8/3,∞)
April 23, 2016

maths
also, we have (x+y)(x-y) = 12 The pairs of factors of 12 are 1,12 2,6 3,4 x+y=6 x-y=2 x=4,y=2
April 23, 2016

math
is the light source between the center of the circle and the object's line, or on the far side of the line? That will affect where the shadow falls. Also, you have not indicated the speed of the object, dx/dt. In either case, label the light source L, the object P and the ...
April 23, 2016

geometry (check answers)
how can a rhombus be sometimes a square, but never a rectangle? a square is always a rhombus a rhombus is sometimes a square so, a rhombus is sometimes a rectangle, since a square is always a rectangle. as for trapezoids, some places define them as a quadrilateral with at ...
April 22, 2016

Calculus I
yes, so using symmetry, the area is a = 4∫[0,1] √(1-(x-1)^2) dx = π
April 22, 2016

HELP ME MATH
the perimeter is just the sum of the sides. So, that is large: 4x+2 + 7x+7 + 5x-4 = 16x+5 small: x+3 + 2x-5 + x+7 = 4x+5 large-small = (16x+5)-(4x+5) = 12x
April 22, 2016

Precal
but -2 is not a solution, since the domain of log(x) is x>0.
April 22, 2016

Program
assuming positive numbers, largest=0 for i=1 to 10 read val if (val > largest) largest=val end for print largest so, what change is needed if positive and negative numbers are allowed?
April 22, 2016

Calculus I
using shells of thickness dx, v = ∫[1,2] 2π(2-x)(x^3-1) dx using discs of thickness dy, v = ∫[1,8] π(2-∛y)^2 dy
April 22, 2016

Calculus I
each square of thickness dx has side 2y, so its area is 4y^2. Adding up all the thin squares, and using symmetry, v = 2∫[0,3] 4(9-x^2) dx
April 22, 2016

Calculus I
using shells of thickness dy, v = ∫[1,3]2πrh dy where r = y and h = x = (y-1)^2 v = ∫[1,3] 2πy(y-1)^2 dy = 40π/3 using discs (washers) of thickness dx, v = ∫[0,4]π(R^2-r^2) dx where R=3 and r=y=1+√x v = ∫[0,4]π(9-(1+√...
April 22, 2016

math
y = k/x^2 That is, x^2y = k is constant. So, you want y such that 19^2 * 9 = 17^2 * y
April 22, 2016

Math
come on. the angles of any quadrilateral sum to 360
April 22, 2016

math
what, can you not answer any of the guiding questions? I'll do #1 For x GB of data, the costs are Runfast: 25+10x BA&D: 18+15x now crank it out
April 22, 2016

Algebra
well, how many of the 52 cards are diamonds?
April 22, 2016

MATHS
no
April 22, 2016

Math
since the opposite of "greater than or equal" is "less than", ~p = ~(x-2 >= 3) = x-2 < 3
April 22, 2016

Trigonometry
sinθ = tanθ cosθ, so tanθ - sinθ = tanθ (1-cosθ) squared that is tan^2θ (1-cosθ)^2 now we can add up the left side: tan^2θ(1-cosθ)^2 + (1-cosθ)^2 = (tan^2θ + 1)(1-cosθ)^2 = sec^2θ (1-cosθ)^2 on the...
April 22, 2016

maths
she walks on a heading, not a bearing. 50@25° = (50sin25°,50cos25°) = (21.13,45.32) add to that (200,0) and you end up at (221.13,45.32) the distance moved is thus 225.73m
April 22, 2016

Math
the sides are in the ratio 1:√3:2 multiply all those by 2.5 and you have a perimeter of (5/2)(3+√3)
April 22, 2016

Math
of the girls, brown: 4/5 long brown: 3/4 * 4/5 = 3/5
April 22, 2016

College Algebra
you know that an exponential function for the value v after t years looks like v = a e^(-kt) at t=0, v=26000, so v = 26000 e^(-kt) v(3) = 18000, so 26000 e^(-3k) = 18000 e^(-3k) = 9/13 -3k = ln(9/13) k = 0.1226 v(t) = 26000 e^(-0.1226t) That's all well and good, but what&#...
April 21, 2016

Math
depends on the size of the container, and how far the ball sank.
April 21, 2016

Calculus
if you draw the square at x, it has a side of length 2y, or 2√(64-x^2) So, the area of the square there is 4(64-x^2) The volume is the sum of all those squares of thickness dx, so v = ∫[0,8] 4(64-x^2) dx
April 21, 2016

math
it is just the base perimeter times the height: 150*5 = 750mm
April 21, 2016

math
the cost c for m messages is c(m) = 10.00 + 0.10m
April 21, 2016

math
175in:70yd = 175in:2520in = 1:14.4 175" is a pretty big drawing!
April 21, 2016

Math
x + 3x+4 = 12
April 21, 2016

algebra HELP PLEASE
72.8/280 = 13/50 = 0.26 pretty steep, since a 6% grade on a highway is considered a steep hill.
April 21, 2016

Trigonometry
sinθ = tanθ cosθ, so tanθ - sinθ = tanθ (1-cosθ) squared that is tan^2θ (1-cosθ)^2 now we can add up the left side: tan^2θ(1-cosθ)^2 + (1-cosθ)^2 = (tan^2θ + 1)(1-cosθ)^2 = sec^2θ (1-cosθ)^2 on the...
April 21, 2016

Math
correct
April 21, 2016

math
since (a-b)^2 = a^2-2ab+b^2, just divide the middle coefficient by 2 and square it. (9/2)^2 and 5^2
April 21, 2016

geometry
see the related questions. Same problem, different numbers.
April 21, 2016

Math
x+y = 19 (x+5)(y+5) = 208 now just solve for x and y.
April 21, 2016

Math- PLEASE HELP
using the fact that the acute angles of right triangles are complementary, and that vertical angles are equal, it's pretty easy to determine that HXZ is 31°
April 21, 2016

math
v = s^3 dv/dt = 3s^2 ds/dt so, 3s^2 ds/dt = 5/2 as you can see, the rate of change of the sides depends on the size of the cube.
April 21, 2016

math
v = 4π/3 r^3 dv/dt = 4π r^2 dr/dt when r=5, dv/dt = 4π * 25 * 1 = 100π cm^3/s
April 21, 2016

Math
those logs are just numbers, so x log19 - 5log19 = x log3 + 2log3 x(log19-log3) = 2log3 + 5log19 x = 2log3 + 5log19 -------------------- log19 - log3
April 21, 2016

Math/Precal
2(3^x) = 5 3^x = 5/2 x log3 = log(5/2) x = log(5/2) / log3
April 21, 2016

math- pre calc
or, in QII, x = -12/13
April 21, 2016

Math
http://www.wolframalpha.com/input/?i=y%3D3x%2B1 any function of the form y=mx+b where m and b are numbers, is just a straight line.
April 21, 2016

Grammar
#1 is better, but it's kind of useless. Of course usefulness is valuable, or it would not be useful. I can think of a context where #2 is syntactically correct, but it's kind of weird.
April 21, 2016

Chemistry - Answer Check
looks good to me.
April 21, 2016

probability
ok - now what?
April 21, 2016

math
EF = 3*BC = 18
April 21, 2016

Math
for that person and that speed, c(t) = 420t if the other factors are variable, then you need a more general function including weight and speed: c(w,s,t) no idea what that would look like, but c(154,15,t) = 420t
April 21, 2016

math
since y increases in steps of 3, the rule will be something like y = 3x + b
April 21, 2016

Precalculs
one way: Ax=B, so you want A^-1 so that x = A^-1 B A = (1 2 3) (-1 2 -1) (-1 1 -2) B = (7) (1) (-2) A^-1 = 1/2 * (3 -7 8) (1 -1 2) (-1 3 -4) Now if you supply the missing value in B, you can do the multiply and get (-1 1 2), the solution. http://www.wolframalpha.com/input/?i=...
April 21, 2016

math
15 <= 2.54W <= 17 9 <= 2.54L <= 11
April 21, 2016

Precalculs
one way: Ax=B, so you want A^-1 so that x = A^-1 B A = (1 2 3) (-1 2 -1) (-1 1 -2) B = (7) (?) (-2) A^-1 = 1/2 * (3 -7 8) (1 -1 2) (-1 3 -4) Now if you supply the missing value in B, you can do the multiply and get (x y z), the solution. Or, you can do row operations as in ...
April 21, 2016

Algebra
a+b+c = 54 c = a+b-4 3a = c+4 now start substituting to solve
April 21, 2016

mathe
that's a strange shaped Egyptian, but assuming he is pyramidal in shape, the height h is found using h^2 = (100/2)^2-50^2 huh? If the sides have a slant height of half the base width, the pyramid is totally flat!
April 21, 2016

math
V = H*W*L just multiply the dimensions. the result will be in units of m^3.
April 21, 2016

Math
I think C is farther out than D.
April 21, 2016

Pre-Calc
review your basic trig functions, and you will that the height h (in miles) can be found using h cotx - h coty = 3
April 21, 2016

sequences and Series
or check the related questions, where it has been solved.
April 21, 2016

maths
The amount donated starts at 10, then grows by 6 each week. So, the donated amounts are 10,16,22,28,... So, the donated amount for the nth week is an arithmetic progression with a = 10, d=6 The total donations in 20 weeks is thus S20 = 20/2 (2*10 + 19*6) = 1340 Add that to the...
April 21, 2016

Ratios!!!!
#8 2x+3x+4x = 63 x = 7 So, the actual quantities are 14:21:28 #9 3ab/27ab = 1/9 So, A,B,E are the equivalent ratios. D doesn't get rid of the a,b stuff. Odd how you could get B and E right, but miss A and pick D... #10 B and D only
April 21, 2016

math
you are correct
April 21, 2016

math
1C is correct
April 21, 2016

Math
Reiny did this already at http://www.jiskha.com/display.cgi?id=1461201861
April 21, 2016

Math
organize things a bit better y = 3x^2+4x-8 y = 2x^2+4x-3 so, 3x^2+4x-8 = 2x^2+4x-3 x^2-5 = 0 x = ±√5 now use that to find y.
April 21, 2016

Dosage calculations
since the rate is 125ml/hr, why does it say 150 ml/hr? Anyway, your calculations look good. but watch the units. 1000ml/8hr = 125 ml/hr, not 125ml 125ml/hr * 3hr = 375ml
April 20, 2016

Math
6C4 .4^4 .6^2 = 0.138
April 20, 2016

math
after t years, p(t) = 23000 * 1.025^(t/8) so, p(25) = 24845 p(-10) = 22301
April 20, 2016

Math
dp/dt = -.06p dp/p = -.06 dt lnp = -.06t p = c e^(-.06t) where c is the starting value.
April 20, 2016

Math
your complex number is garbled.
April 20, 2016

Math
sine the rate of decrease is 14% of the amount present, dp/dt = -.14p dp/p = -.14 dt lnp = -.14t + c p = c e^-.14t here, c is the original amount when is only .22 left? e^-.14t = .22 -.14t = ln.22 t = ln.22/-.14 = 10.8 years
April 20, 2016

Geometry
well, I don't have a diagram, but if the pentagonal shape is just a rectangle with a triangle on top, its area is 8.5 * 17 + 1/2 * 17 * √(12^2-8.5^2) = 216.5 in^2 The round pizza has an area of 49π = 153.9 in^2 So, the cost of the home-plate pizza should be $10....
April 20, 2016

Math
Not sure what that description means, but if it is a cylinder atop a cone of radius 5 and height 4, then its volume is π/3 * 5^2 * 4 + π * 5^2 * 2 = 250π/3 So, the bottom cone must have the same volume: π/3 * 6^2 h = 250π/3 36h = 250 h = 250/36 = 6.9 cm
April 20, 2016

math log rules / chemistry
picking up where you left off, and fixing the minus sign you lost, (E2-E1)/0.05916 = -log[F+S] + log[F] (E2-E1)/0.05916 = log(F/[F+S]) 10^[(E2-E1)/0.05916] = F/(F+S) 10^[(E2-E1)/0.05916]F + 10^[(E2-E1)/0.05916]S = F F = 10^[(E2-E1)/0.05916]S ------------------------------ (1-...
April 20, 2016

help azap
length is ft area is length*width = ft*ft = ft^2 volume is length*width*height = ft*ft*ft = ft^3
April 20, 2016

Statistics
play around with Z table stuff here: http://davidmlane.com/hyperstat/z_table.html
April 20, 2016

math
no solutions. |x+1| is never negative, so adding 6 can never give a sum of 3. trick question.
April 20, 2016

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