Saturday

July 4, 2015

July 4, 2015

Total # Posts: 32,091

**calc(very urgent)**

something wrong with the solution I posted a few hours ago? http://www.jiskha.com/display.cgi?id=1429156887
*April 16, 2015*

**precalculus**

we know that the center is at (0,0) and the axis is vertical, so y^2/a^2 - x^2/b^2 = 1 If the distance between the vertices is 2a = 8, then 4^2 + b^2 = c^2 Since (3,-5) is on the graph, 25/a^2 - 9/b^2 = 1 a=4, so 25/16 - 9/b^2 = 1 b^2 = 16 y^2/16 - x^2/16 = 1 See the graph at ...
*April 16, 2015*

**pre-calc**

You have Sn, but you have a typo, or the copy/paste mangled it. It should be Sn: 1^2+...+(3n-2)^2 = n(6n^2-3n-1)/2 So, S1: 1^2 = 1(6*1^2-3(1)-1)/2 S2: 1^2+4^2 = 2(6*2^2-3*2-1)/2 S3: 1^2+4^2+7^2 = 3(6*3^2-3*3-1)/2 which are all true We have not shown it to be true for all n. To...
*April 16, 2015*

**pre-calc**

8x+7y >= 336 Unless we're discussing pirates, that's borders.
*April 16, 2015*

**math**

well, clearly, the marble has a height of 2r, so the water must be that deep to cover it. Since the cylinder is said to have a radius of 4, I think you want the radius of the marble that requires the most water to cover it. The volume of water is v = π*16(2r) - 4/3 π...
*April 16, 2015*

**pre - CALCULUS**

enter your values here to see all the details: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*April 15, 2015*

**Pre-calculus**

vehicles and winds travel on a heading, not a bearing. Sadly, this distinction is ignored or unknown to many textbook writers and teachers. But on to the math. the Cessna in still air travels be at (180 sin35°,180 cos35°) = (103.24,147.45) The wind blows it an ...
*April 15, 2015*

**calculus (please help. URGENT!)**

v = π/3 h^2 (3r-h) = πrh^2 - π/3 h^3 dv/dt = 2πrh dh/dt - πh^2 dh/dt = πh(2r-h) dh/dt Pluggin in your numbers, then, we have π*5(20-5) dh/dt = 3 dh/dt = 3/(75π) = 0.021 m/min
*April 15, 2015*

**Math (ASAP)**

well, just plug and chug a1 = 32 a2 = 1/2 (32) = 16 a3 = 1/2 (16) = 8 ...
*April 15, 2015*

**math**

I got 111.32, so I guess it depends on how you want to round it.
*April 15, 2015*

**Math**

4321 = 29*149 we know that 149 divides the product, so the question is, is any other number in teh product a multiple of 29? There are only 21 consecutive factors, so it's not guaranteed, so you'll have to check whether there is a multiple of 29 between 140 and 160. ...
*April 15, 2015*

**Math**

oops. 10*42^2 = t*60^2
*April 15, 2015*

**Math**

t = k/v^2 so, tv^2 is constant. Therefore, 10/42^2 = t/60^2
*April 15, 2015*

**Science/Physics**

3.9 + 2.4 + (3.9+3.1) = 13.3 How did you arrive at 10.5?
*April 15, 2015*

**geometry**

the midpoint is the average of the endpoints. So, for BC, P=(h,k) Now just use your distance formula to get the required lengths.
*April 15, 2015*

**math**

plug in your numbers and play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html
*April 15, 2015*

**math**

.42
*April 15, 2015*

**even wurse spelling**

yet correct, withal.
*April 15, 2015*

**More math**

and yes, you are correct.
*April 15, 2015*

**maths**

after 6 jumps, he has descended 6 steps The 7th jump will take him to the 9th step.
*April 15, 2015*

**geometry**

The inner rectangle is 70x105 the inner circle has radius 35 the outer rectangle is 84x105 the outer circle has radius 42 now just figure the areas and subtract inner from outer
*April 15, 2015*

**trig table?**

Excuuuuuse me! How long ago did you take trig? No one uses tables any more. However, the trig book I used was titled "Trigonometry with Tables." I remember our library had huge volumes from the National Bureau of Standards with 12-place tables for trig, log, and ...
*April 15, 2015*

**maths**

PAD is not necessarily congruent to PBC. They have two sides congruent, but that is not enough.
*April 15, 2015*

**Precalc**

f(x) = (3x)^-4 + 3x^4 f' = -4(3x)^-5(3) + 12x^2 = -12/(3x)^5 + 12x^2 where is 15x^2-30x = 0? where is 6x^2+12x = 0?
*April 15, 2015*

**math**

60mph = 88ft/s, so you want k where 88-kt=0 so t = 88/k 88t-1/2 kt^2 = 100 88(88/k) - 1/2 k (88/k)^2 = 100 k = 38.72 ft/s^2 now you can solve the other part.
*April 15, 2015*

**algebra**

recall that the slope-intercept form of a line is n = mt+b where m is the slope. Here, that is -2.23 It means that the number of refineries is declining by 2.23 per year, or about 9 refineries every 4 years.
*April 15, 2015*

**math**

(20+14)(30+14)-(20)(30)
*April 14, 2015*

**math**

just using the measurements, the tiled area is 8*6 - 2*3 = 42 ft^2 11" is nearly a foot, so we can estimate that about 42 tiles will be needed. Naturally, since the tiles are a bit smaller, more of them will actually be used.
*April 14, 2015*

**geometry**

Assuming a logical arrangement of W,X,Y,Z, your answer appears correct.
*April 14, 2015*

**math**

recall that the product of the roots of ay^2+by+c=0 is c/a. Here, a is 1, so y1*y2 = -c clearly, 12 and 0 only work if c=0. suppose c is -36. The roots are 6 and 6.
*April 14, 2015*

**AP CALC**

looks good to me.
*April 14, 2015*

**calculus multiple choice**

#1 v = ∫[0,lnπ] π sin^2(e^x) dx That will take some numerical methods to figure. #2 ∫[1,3] 2/x dx ----------------- 3-1 #3 s(t) = ∫[0,2] -2t^2+4 dt
*April 14, 2015*

**PRE - CALCULUS**

so, did you graph it?
*April 14, 2015*

**Chemistry**

1.05 g/mL * 5500 mL * 1lb/454g = ? lb
*April 14, 2015*

**Science**

all are metals except sulfur
*April 14, 2015*

**Technical Physics**

it falls the anchor displaces its volume in water when it sinks, but it displaced its weight when it was in the boat.
*April 14, 2015*

**maths**

-2*2*5
*April 14, 2015*

**math**

for the same reason that spelling should
*April 14, 2015*

**math**

what makes you think anyone "found" it?
*April 14, 2015*

**Physics**

after 25 seconds, v=25*.8 = 20 when it starts to decelerate, a = -1 m/s^2, since it takes 20s to decrease v to 0. so, the total distance is s = 1/2 .8*20^2 + 20*77.5 + 20*10 - .5*400 = 1710 m avg speed is thus 1710/(20+77.5+20) m/s
*April 14, 2015*

**Pre-Calculus (Check)**

If the middle table has side x, then the three squares (x-1)^2 + x^2 + (x+1)^2 = 677 3x^2 + 2 = 677 3x^2 = 675 x^2 = 225 x = 15 and the tables have sides 14,15,16 how did you come up with 3x^2-6x = 677?
*April 14, 2015*

**physics**

correct.
*April 14, 2015*

**Math**

#1 is correct #2 is 11 it is a vertical line whose y-coordinates differ by 11, so that is its length. How did you come up with 18?
*April 14, 2015*

**Fourier Series**

well, you have to break f(x) into two parts for x<0, f(x) = 0 for x >= 0, f(x) = 2x so, a0 = 1/π ∫[0,π] 2x dx = π and for the others just use integration by parts for integrals of x cos(nx), etc.
*April 14, 2015*

**Math**

(12.7*7.5 m^2) * (10.76 ft^2/m^2) * (1 bdl/33ft^2) * ($29.95/bdl) = $930.17 That is the cost for one side of the roof. The cost will actually be a bit higher if only whole bundles can be purchased.
*April 13, 2015*

**Polygons on the coordinate plane**

plural of vertex is vertices. So, draw a rectangle where the length + width = 8.
*April 13, 2015*

**Calculus**

oops.The printed area is 8x12, so the page is 10x15
*April 13, 2015*

**Calculus**

If printed area has height y and width x, then the page size is (x+2) by (y+3) Since xy = 96, the page size s = (x+2)(y+3) = (x+2)(96/x + 3) ds/dx = 3 - 192/x^2 so, ds/dx = (3x^2-192)/x^2 which is zero when x=8 so the page is 10x11 So, how do our calculations differ?
*April 13, 2015*

**calculus**

x^2+y^2 = 225 so, x dx/dt + y dy/dt = 0 Now plug in your numbers and solve for dx/dt
*April 13, 2015*

**Math**

original: v 1st reduction: v^2 2nd: v^4 3rd: v^8 so, v^8 = 27/125 v = (3/5)^(3/8)
*April 13, 2015*

**math 8th grade**

there are 12 face cards P(J,K) = 4/12 * 4/11 P(b,b) = 6/12 * 5/11
*April 13, 2015*

**calculus**

Each square cross-section has width y and height y, so its area is y^2 = 9e^(-2x) So, the volume is the sum of all those squares, or ∫[0,2] 9e^(-2x) dx
*April 13, 2015*

**Math**

The slope of line MN is 0. So, every point has y-coordinate 3. Thus, 2a=3 and P = (3/2,3)
*April 13, 2015*

**Pre-Calc**

they are expressions. You surely know the exact value of cos(30°) as for sin(-3π/5) you would have to construct a pentagon and figure out some side lengths. figure out sin 36° and then sin 72° and then the sine of 108°.
*April 13, 2015*

**Pre-Calc**

1) that would be cos(12°+18°) which I'm sure you know 2) sin(4π/5-7π/5) 3) well, tan/cos = sin/cos^2 and sec = 1/cos
*April 13, 2015*

**Math**

w = 3b
*April 13, 2015*

**What does this mean**

they want between 400 and 500 words. That should fit on two pages.
*April 13, 2015*

**pre - CALCULUS**

well, you know that x=2y-5 so, substitute that into the other equation, solve for y, and then you can get x.
*April 13, 2015*

**MATH**

495,000 501,000 or any other numbers close to 500,000
*April 13, 2015*

**geometry**

40*20*h = 12000 h = 15 so, you want the surface of the bottom and sides of a box 40x20x15 cm.
*April 13, 2015*

**Intermediate Algebra**

There is no solution to #1 since 12 is not less than 0. As written 12 < 12 + 4x < 0 means 12 < 12+4x AND 12+4x < 0 To find such a number, you would need 12 < 0 12 – x > 15 or 7x – 13 > 1 12-x > 15 -3 > x 7x-13 > 1 7x > 14 x > 2 You...
*April 13, 2015*

**Calculus**

If the steel side is x, then xy = 870 and the cost c = 2x+4*2y so, sub in x or y and find dc/dx or dc/dy
*April 13, 2015*

**Algebra 1**

well, when is 4x-8=0?
*April 13, 2015*

**Algebra 1**

What is the excluded value of the rational expression? 2x+6 / 4x-8
*April 13, 2015*

**Pre - CALCULUS**

If you mean x^2/36 + y^2/11 = 1 then you can see that since 36 > 11, the major axis is on the x-axis. So, since b^2+c^2 = a^2, c^2=25, and the foci are at (±5,0)
*April 13, 2015*

**Pre Algebra Probability**

correct
*April 13, 2015*

**pre - CALCULUS**

That's a sigma 4 ∑ (-1)^k (k+11) k=1 = (-12)+(13)+(-14)+(15) = 2
*April 13, 2015*

**Scientific Notation**

1.0*10^-4 -------------- 2.0*10^-9 = 0.5 * 10^5 = 50,000
*April 13, 2015*

**Algebra**

well, just add up the lengths. If the first shelf is x, then x + (2x+18) + (x-12) + (x+4) = 2.5 Now find x, and the 2nd shelf is 2x+18
*April 13, 2015*

**math**

The tip of your little finger is about 1 ml. So, what do you think?
*April 13, 2015*

**Algebra 1**

when the heights are equal, t seconds after B's launch, 220(t-.25)-16(t-.25)^2 = 220t-16t^2 t = 7.0
*April 13, 2015*

**Math**

do you know how many cups in a quart?
*April 13, 2015*

**math**

well, 6 is 96/16, so r = 1/2
*April 13, 2015*

**Algebra 1**

(x+8)^2 - x^2
*April 13, 2015*

**Algebra 1**

thank you
*April 13, 2015*

**Algebra 1**

The size of a computer monitor is given by the length of the diagonal of the screen.The ratio of the height to the width of wide screen monitors is 9:16. Find the expressions for the width and height of a wide screen monitor in terms of the lengthy of its diagonal.
*April 13, 2015*

**Algebra 1**

In a right triangle the adjacent side = 12, the opposite side = 35, and the hypotenuse = 37. What does the opposite angle =? a-71,1 deg b-18.9 deg c-29.2 deg d-90 deg my answer is 18.89 degrees
*April 13, 2015*

**math**

-2h-21+4h <= 9 2h-21 <= 9 2h <= 30 h <= 15
*April 13, 2015*

**Pre-Calculus**

Looks to me like you need -3(x-2)^2 + 13
*April 13, 2015*

**Math???Help**

Assets are + Liabilities are - 235000 -170000 +17900 -5900 -823 +1200 ------------- 77377
*April 13, 2015*

**Math**

what are all those *'s supposed to mean?
*April 13, 2015*

**Algebra 1**

sorry copied answer wrong 27y sqrt 15
*April 13, 2015*

**Algebra 1**

sqrt 15y * 3 sqrt 81y Simplify the radical expression My answer is 27 sqrt 15y^2
*April 13, 2015*

**algebra**

60 burgers and a dozen sodas.
*April 13, 2015*

**math**

dunno. what are the little boxes?
*April 13, 2015*

**algebra**

so, what's the problem? 5.2x-x^2 = 4.8 x^2-5.2x+4.8 = 0 Now just use the quadratic formula to find x. It may be that one of the solutions does not apply, depending on the size of the pipe.
*April 13, 2015*

**math**

clearly, f(a-1) = (a-1)^3-3 That's good as it is, but you might want to expand the binomial power.
*April 13, 2015*

**math**

do you mean (t+1-t^3)^2 or t^2+1-t^3 either way, just replace all the t's with 2's and evaluate the result.
*April 13, 2015*

**algebra,mathematics**

first part already answered I suspect a typo, what with the -x and +x, leaving you with √2 x^2-5=1 √2 x^2 = 6 x^2 = 6 hmmm. not what you expected. How about √(2x^2)-5=1 2x^2=36 x^2=18 Hmmm. Better clean up your notation a bit.
*April 13, 2015*

**maths**

A false B true C true, if you allow complex values. Otherwise, it has no real values at all.
*April 13, 2015*

**math**

as on your other post, use what you have. Since 6y = 3(2y), 5x-3(3x-13)=23
*April 13, 2015*

**math**

well, if you have 5 numbers whose mean is 19, then they must add up to 5*19 = 95 Your sum so far is 58 So, you need two more numbers which add up to 37. Since your median is 19, you need one less than 19 and one greater than 19. So, how about 14 17 19 20 25 You can surely find...
*April 13, 2015*

**math**

r(18c-3d-6+d) I suspect a typo, as that's as far as you can go with what you have. Note that you have 2y=3x-13 So, use that in the other equation to get 5x-(3x-13)=23 Now just solve for x, then get y from that.
*April 13, 2015*

**trigonometry**

A) a = 1/2 r^2θ, so 21 = 1/2 r^2 25π I gotta wonder about an angle of 25π, since 2π is a complete circle... B) 487π = 243(2π) + π C) 1/365 * 2πr
*April 13, 2015*

**PHYSICS math**

If the problem was presented in this language, that's some poor textbook! The distance d (in km) of the plane from you?, me?, them? might be d^2 = 2.1^2 + 1.5^2 + 50^2 In the x-y plane, the angle is arctan(1.5/-2.1)
*April 12, 2015*

**ALGEBRA PLSSSSSS**

Suppose you had x^3-10 = 0 Then the only real zero would be x=∛10, right? Well, this is the same thing. The only real zero is x-12 = ∛10, or x = 12+∛10 The graph is just like the graph of x^3-10, but shifted right by 12.
*April 12, 2015*

**9th grade geometry**

well, that'd just be the sum of the two volumes, right? cone: 1/3 πr^2h = π/3 (6^2)(8) cylinder: πr^2h = π (6^2)(10)
*April 12, 2015*

**calc rates**

draw a cross-section. When the water has depth y, the radius of the surface is r = 3/14 y So, the volume of the water at depth y is v = 1/3 πr^2y = π/3 (3/14 y)^2 y = 3π/196 y^3 dv/dt = 9π/196 y^2 dy/dt If the water is being pumped in at a rate of k cm^3/...
*April 12, 2015*

**calc rates**

dS/dt = 8πr dr/dt dV/dt = 4πr^2 dr/dt so, dV/dt = r/2 dS/dt dS/dt = dV/dt * 2/r The given data thus mean that dS/dt = 500*2/11 cm^2/min
*April 12, 2015*