Wednesday
April 23, 2014

Posts by STEVE


Total # Posts: 21,927

Algebra
xy=k is the inverse variance equation Since 8*6 = 48, we have xy = 48 or y = 48/x

Math
The problem can't be made any simpler. The expression, however, can be simplified by collecting like terms: x(1-1) + y(4+3) + z(-5-6) 0 + 7y - 11z 7y-11z or, maybe it would be simpler to ditch the parens and then reorder the variable terms: x+4y-5z-x+3y-6x x-x +4y+3y -5z-6...

Algebra
well, you can surely see that √144 = 12 √c^14 = c^7 so, 2*12*c^7 24c^7

Trigonometry
hard to tell, since we don't know where the sun is. Better clarify a bit, by labeling points (A,B,C) and distances and angles.

Calculus
take a look at this article: http://mathworld.wolfram.com/RiemannSum.html you can estimate the true area under the curve by drawing rectangles under the curve and adding up their areas. But, wince the rectangles have flat tops, they don't really fit the curve. So, pick eit...

math
Since 9*2 = 6*3, the big pully turns 2 times while the small pulley turns 3 times So, 3/2 * 1200 = 1800

math
Since E and F are the midpoints of their sides, we are talking about medians of a triangle. The medians meet 2/3 of the way from the vertex to the side. So, AD/DF = 2 CD/DE = 2 AD x CD/DF x DE = AD/DF * CD/DE = 4

calculus help
actually, I do see a mistake. C2 = 0 C1 = 69/4 s(t) = 1/12 t^4 - 5/6 t^3 + 7/2 t^2 + 69/4 t

calculus help
well, pretty sure. Do you see any errors in my work? wolframalpha agrees with me. http://www.wolframalpha.com/input/?i=solve+y%22+%3D+x^2-5x%2B7+where+y%280%29%3D0+and+y%281%29%3D20

calculus help
a = t^2-5t+7 v = 1/3 t^3 - 5/2 t^2 + 7t + C1 s = 1/12 t^4 - 5/6 t^3 + 7/2 t^2 + C1*t + C2 plugging s(0) and s(1), we have C1 = 0 1/12 - 5/6 + 7/2 + 0 + C2 = 20 C2 = 69/4 so, s(t) = 1/12 t^4 - 5/6 t^3 + 7/2 t^2 + 69/4

math
rearrange things a bit and you have a = x+1 b = x-1 so, ab = (x+1)(x-1) = x^2-1

Algebra 2
just plug in the numbers and solve for t in -16t^2 + 32t + 100 = 0 t = 3.69

math
the area of the square is 2^2, but the diameter of the circle is the diagonal of the square. Since the side is 2, the diagonal is 2√2 The radius is half the diameter, or r = √2 the area of the circle is thus pi r^2 = 2pi

algebra
adding up the value of each part needs to equal the value of the total mixture. So, if x lbs of cashews are used, 7.00x + 5.50(35-x) = 6.50(35) x = 23 1/3 lbs cashews

Algebra Work Check
In that case, you are correct. The expressions are complicated enough that if you came up with the correct answers, your process was likely correct.

Algebra Work Check
5√6 * 1/(6√216) 5√6 * 1/(6*6√6) 5/36 If you meant -9√(28a^2) * 1/(3√(63a)) -9(2a√7) * 1/(3*3√(7a)) -18a√7 / 9√7√a = -2√a

Physics
we want <200cosθ,200sinθ> + <-50,0> = <0,v> 200cosθ = 50 cosθ = .25 θ = 75.5° v = 200sinθ = 200*.968 = 193.6

geometry
3(90-x) = 30+(180-x)

Geometry
since she is on the edge of the green, the ball travels at a right angle to the line to the hole. So, now we have a right triangle with legs 8 and 20. The distance from the ball to the hole is the hypotenuse, of length √(8^2+20^2)

programming
when your program loads and runs, it occupies a certain amount of memory, for instructions, data storage, etc. As it runs, it may need additional memory space to store more data, or load new instructions. So, one of the system subroutines is a call to malloc or some equivalent...

programming
memory leaks occur when memory allocated by the program is not returned to the operating system. As time passes, more and more memory is consumed, and eventually the program (or the operating system!) crashes.

math
solve for r in compound interest: 3000(1+r)^4 = 4105.71 simple interest: 3000(1+4r) = 4105.71

Circle geometry
it is a right angle. The central angle is 180° An inscribed angle is 1/2 the central angle. Check your theorems.

geometry
the area is 1/2 r^2 θ = 1/2 * 2.9^2 * 160/180 π = 11.74 The central angle of an octagon is 45°. area = 1/2 apothem * perimeter = 1/2 (4/tan 22.5°) * 8*8 = 309.0

Algebra II
luckily, the answers agree!

ALG> and graphs
from the center, you know the equation is (x-4)^2 + (y-1)^2 = r^2 Now just plug in your point, which lies on the circle: (8-4)^2 + (-2-2)^2 = r^2 r^2 = 32, so (x-4)^2 + (y-1)^2 = 32

math
or, look at it as a scaling problem. In a right triangle with legs 2 and 3, the hypotenuse is √13, and the area is (1/2)(2)(3) = 3. Your triangle has a an of 48, which is 16*3 Since the area scales as the square of the scale factor, the hypotenuse is 4*√13 = 2ͩ...

Algebra please help
11000(1+.03/4)^(4*9)

algebra
√(3x+4) + 4 = 2x √(3x+4) = 2x-4 3x+4 = (2x-4)^2 3x+4 = 4x^2 - 16x + 16 4x^2 - 19x + 12 = 0 (4x-3)(x-4) = 0 x = 3/4 or 4 But, squaring sometimes introduces extraneous roots. In this case, x = 3/4 does not work. √(3*3/4 + 4) + 4 = 2(3/4) √(9/4 + 4) + 4 = ...

math
% increase is the absolute increase as a fraction of the original amount: x/a = 100x/a %

algebra
place all over the common denominator: (x-3)(x+3) and you have 12 + 3(x-3) = 2(x+3) 12 + 3x-9 = 2x+6 x = 3 But, 2/(x-3) is undefined in the original equation. The domain of f(x) excludes 3 and -3.

Algebra II
P(<10 | blue) = P(<10) + P(blue) - P(<10 & blue) = 9/100 + 50/100 - 5/100 = 54/100 similarly for (b)

Maths
1 0 0 -15/2 0 1 0 -24 0 0 1 -21/2

Maths
8 7 -4

geometry
I dunno 95° and 101° ? 120° and 200° ? I think there's something missing here.

science
I think you have garbled your values. If the speed of sound is 100 km/hr and the plane is already going 600 km/hr ... At any rate, when you get the speeds figured out, the number of seconds it takes is just the extra speed needed divided by 10, since the speed increases 10km/h...

Math
My bad. You are correct. I dropped a 3 after the 2nd line. But then, you caught that when you checked my math. Right?

Math
-9 √(28a^2) * 1/3 √(63a) -9 * (2a√7) * 1/3 (3√(7a)) -6a √(49a) -42a√a

math
2+2=4 That's always a good place to start...

Math - incomplete
no idea - no picture.

math
unserved customers: c-16 tellers available: 4 so, (c-16)/4

triangle measurements
no joy, mia. Take two sticks of those lengths, and lay them side by side, with one end flush. Now start separating the other ends. You can easily see that any of the lengths 3,4,5,6 is possible, depending on how widely you open the angle.

math
42000(1.11)^19 = 305060.44

Math
1 yd = 36 in, so 288 in * 1yd/36in = 8 yd

TRIG
√(1-√21/5)/2) This is sin x/2 where cosx = √21/5 the value is

Math
you don't say which intercept. If you want the x-intercept, that's where y=0, so -x+0 = -6 x = 6 (6,0) is the x-intercept If you want the t-intercept, that's where x=0, so 0+3y = -6 y = -2 (0,-2) is the y-intercept. If you have the ordered pair (3,?), plug in x=3 a...

Calculus
u = x^2+5 du = 2x dx So, your integral is now 1/2 ∫ du/u u= lnx du = 1/x dx ∫sin(u) du

math check
I don't see any outliers. All the values appear to lie near a sloping line. Plot the points and see whether any is obviously more distant than the others.

Math 10
given the vertex, you know that y-2 = a(x+1)^2 Since (1,-10) is on the graph, -10-2 = a(1+1)^2 -12 = 4a a = -3 y-2 = 3(x+1)^2

calculus help
sure you do. a(t) = 3t v(t) = 3/2 t^2 + c but, v(2)=0, so 3/2(4)+c = 0 c = -6, so v(t) = 3/2 t^2 - 6 s(t) = 1/2 t^3 - 6t + c but, s(2)=1, so 1/2 (8) - 6(2) + c = 1 c = 9 s(t) = 1/2 t^3 - 6t + 9

math
If he rode x minutes after lunch, then 5x-1 + x = 41 x = 7

math
w + r = 50 w + 6w+1 = 50 w=7, so r=43

Math
rhombus

Math
(84*1.15)/5 = ?

Algebra
just pick easy values for x. That 4/5 out front makes it likely to use multiples of 5. So x y -5 1 0 5 5 9 10 13 For every 5 x increases, y grows by 4. (Since the slope is 4/5)

math
a complete circle has 360 degrees. So, 1/12 of a circle (a slice) has 30 degrees. So, how many degrees in the 5 uneaten slices?

math
3/2 the diameter means 9/4 the volume. So, the small cylinder fills 4/9 of the big cylinder. 4/9 * 10 = 40/9 inches of juice.

MATH GEOMETRY
20

Geometry MATH
draw it. It's a parallelogram with base=6, height = 3 So, area = bh = 18

Geometry
How wide are the rolls?

Geometry
bases are 6 slanting sides are √13

Math mrs.sue plz help i a confused.
m = -2 m = 2 m is the change in y divided by the change in x. So, for #1, y changes from 4 to 6 (+2) x changes from 3 to 2 (-1) 2/-1 = -2

statistics
950-1050 or, above 1168 or, below 832 or at least 256 away from 1000 You can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html

Algebra
pi r^2 (2r+1) = 20pi 2r^3 + r^2 - 20 = 0 r = 2 I guess you can probably figure out what h is, no?

Computer Programming
sounds correct to me. read the scores into the array find the average scan the array, counting those above and below.

Science
can you look up into the sky and see the moon? yes or no.

math (SIMPLE INTEREST)c
left in 1995: 12+31 = 43 days to go in 1996: 31+29+31+30+1 = 122 days no idea what rules you use for approximate time. 19 Nov - 19 May is 6 months, or 180 days (using the 360-day year). Knock off 18 days in may to get 162 days

Networking
firm is assigned the network part 128.171. It selects a 10-bit subnet part. a) Draw the bits for the four octets of the IP address of the first host on the first subnet. (Hint: Use Windows Calculator.) b) Convert this answer into dotted decimal notation. c) Draw the bits for ...

math (SIMPLE INTEREST)
.12x + .08(3000-x) = 3200 now just solve for x, the amount at 12% I can tell you right now that there's a typo in there somewhere.

math (SIMPLE INTEREST)
think about it. In 4 years you have added 100% So, that's 25% per year.

Algebra - HELP!!!
Ah. I never thought that would be a problem. I copied/pasted from your posting. yes, you are correct in your interpretation. the perils of word processors which use em-dashes instead of ascii minus signs.

Algebra - HELP!!!
–16t^2 + 85 = 0 when t = √85 / 4 for 20 and 21, can you not see the - signs or their absence? as for y, the x values are the solution when y = zero!

Algebra - HELP!!!
#1: range: (–∞, 0] graph: parabola opening downward. since x^2 is always positive, -.5x^2 is always negative #2: It is shifted 5 units down. take a look at http://www.wolframalpha.com/input/?i=plot+y+%3D+-2x^2%2C+y%3D-2x^2-5 #3:ok #4: I get 88.5 m. See http://www.wo...

Math
I assume you mean to expand the product. If so, that would be 9*4 + 9*r = 36+9r

Math
first, fix the typo. Then, enter your function at http://rechneronline.de/function-graphs/ for excellent graphing help. You can adjust the x- and y-ranges to shift and scale the graph.

math- Calc
v = 4/3 pi r^3 when v = 1000, r = ∛(3000/(4pi)) dv/dt = 4 pi r^2 dr/dt Now just plug in your values for dv/dt and r to get dr/dt.

alg.
I'll do the first. If you get stuck on #2, come on back with whatcha got. y = x+4, so x+4 = x^2-x-4 x^2-2x-8 = 0 (x-4)(x+2) = 0 x = 4 or -2

math
40% are girls. So, what is .40 * 480 ?

algebra
we know that 3 points define a plane. So, pick 3 points and determine the normal direction to their plane. Now replace any of the points with the 4th point, and determine the new normal. If the two normals are the same, the 4 points are coplanar. If we label the direction vect...

english
In the giver why was Gabriel in danger of being released?

english
In the book Giver -- the committee of elders consulted the giver for what?

Math
5

math
If he purchased x shares for price p, then xp = 176 But, (x+5)(p-5) = xp xp + 5p - 5x - 25 = xp p-x-5 = 0 but, p = 176/x, so 176/x - x - 5 = 0 x = 11 11*16 = 176 16*11 = 176

math
3x3=9 tiles per sq. ft. 11*14*9 = ?

math
(-3+4,4) = (1,4)

Math
I'd say the money. It comes in discrete amounts. The electricity changes smoothly as the refrigerator runs. Even during on/off transitions, the voltage and current cannot change instantly.

math
the class of 24 students has 16 females. So, in both cases, we have male:female = 8:16 This is only true because male and female are the only possible choices.

Math
C(x) = 10/3 x 10cal/3mints = 10/3 cal/mint

Calc
y = 4√(x+2) The distance from the particle to (0,0) is d = √(x^2+y^2) = √(x^2 + 16(x+2)) = √(x^2+32x+16) At(1,8), d =√65 Since d^2 = x^2+32x+16, 2d dd/dt = (2x+32) dx/dt At (1,8), then 2√65 dd/dt = 34*5 = 170 dd/dt = 85/√65

calculus help - not so fast
good work, Damon, but we are give the derivative. The rational function is f'(x), not f(x).

Algebra help PLEASE?
(D) (C) The first is (B) if you meant -4 instead of 14.

math
a = 6 ar = a+3d ar^2 = a+9d so, d = (ar-a)/3 ar^2 = a+9a(r-1)/3 r^2 = 1+3r-3 r^2-3r+2 = 0 r = 1 or 2 since the GP terms are different, r=2 and d=2 and the sequences are 6,12,24 6,8,10,12,14,16,18,20,22,24

Math
any polynomial of degree n has n roots The Fundamental Theorem of Algebra

algebra
just plug in the proper conversion factors: 84 ft/1hr * 12 in/1ft * 1hr/60min = (84*12*1)/(1*1*60) in/min

math
the ratio of shadow/height is constant, so 12/5 = x/17.5 or, the height and shadow scale the same way, so since 17.5 is 3.5 times 5, the shadow will be 3.5 times 12 feet long.

Math
(1,1/2) You know, you don't really need us to verify your answers. Just plug them into the equations and see whether they work. If you run into trouble, post your work, and we can help figure what went wrong.

Math
(0,-1/2)

Math ~ Check Answers ~
#1 ok #2: there are 4 numbers greater or equal to 3: 3,4,5,6 #3 ok #4 nope. 3:1 against, 1:3 in favor

ALG. REPOST TYPO
recall that the vertex of x-h = a(y-k)^2 is at (h,k). Look at your function and you see that x-4 = -1/3 (y-0)^2 so the vertex is at (4,0) Now use your knowledge that the vertex lies on the axis of symmetry, and you're almost home free.

ALG
y = 8(x^2+6x) - 3 now just complete the square. y = 8(x^2+6x+9) - 3 but wait. You just added 8*9, so subtract it off so things don't get changed. y = 8(x^2+6x+9) - 3 - 8*9 y = 8(x+3)^2 - 75 now it's easy to see that the vertex is at (-3,-75), and of course, it lies on ...

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