Sunday

October 4, 2015
Total # Posts: 34,242

**chemistry**

assuming STP for the O2, you have 5.6/22.4 = 0.25 moles O2 5.6g = 5.6/55.85 = 0.10 moles Fe If your reaction is 4Fe + 3O2 = 2Fe2O3 then the reaction consumes elements in the ratio (moles O2)/(moles Fe) = 3/4 Your available reagents are in the ratio of O2/Fe = 0.25/0.10 = 5/2 ...
*August 17, 2015*

**mathematics**

I cannot interpret all those words. What is "by" supposed to mean? Is 3 to power 5by2 2*3^5 or (3^5)^2 That is, does by mean multiply by or raise to a new power? Try using * for multiply ^ for exponent () to make it clear what is grouped Ahhh. I think the "by&...
*August 17, 2015*

**uniuyo**

the 5th terms is the 3rd after the 2nd term, so their ratio is r^3. Thus, r^3 = 567/21 = 27 r = 3 a = 21/3 = 7
*August 17, 2015*

**word problem**

x+y = 38 8+2x = 5y Now just solve for x and y
*August 17, 2015*

**Math**

Just read what they say and start filling in the digits! I am a four digit number xxxx I am between 2,000 and 3,000 2xxx the digit in the ones place is four times as much as the digit in the thousands place 2xx8 Only one of the digits are the same. Ya got me what that means. ...
*August 17, 2015*

**Precalculus**

Since the ratio of radius/height is constant at any water depth (45/6 when full), r = 15/2 h. You want h when v=5000. v = 1/3 πr^2 h, so π/3 (15/2 h)^2 h = 5000 π/3 * 225/4 h^3 = 5000 h^3 = 12*5000/225 = 800/3 h = 6.43m
*August 16, 2015*

**Physics**

conserve momentum: .050v + 7.00(0) = 5.00(.050+7.00) v = 705 m/s
*August 16, 2015*

**word problems**

x+y = 38 8+2x = 5y Now just solve for x and y.
*August 16, 2015*

**math**

with y being the number of tires produced per hour, y = 50 + 10x
*August 16, 2015*

**king george memorial school math**

assuming base 10, we have log(x) + log(y) = 4 log(xy) = 4 xy = 10^4 = 10000 y = 10000/x
*August 16, 2015*

**Physics**

since v = 4/3 πr^3, then the density (mass/volume) is 8.1*10^28kg / (4/3 π*(1.7*10^3)^3)m^3 = 3.936*10^18 kg/m^3 3.936*10^18 kg/m^3 * 2.0*10^-7 m^3 = 7.872*10^11 kg mass = density*volume You divided, and even did that wrong.
*August 16, 2015*

**Maths- calculus**

The length of the kit string is z(t). We have z^2 = 40^2 + (x-k)^2 x' = 1 z' = 1 At the moment in question, x-k = 30, so z=50 2z z' = 2(x-k)(x'-k') 100 = 60(1 - k') 5/3 = 1 - k' k' = -2/3 Seems odd, doesn't it? But a little consideration ...
*August 16, 2015*

**algebra**

well, I guess you also have to add f >= 0 c >= 0
*August 16, 2015*

**algebra**

If there are f lbs of fish and c lbs of chicken, then 11 <= 4f+3c <= 15
*August 16, 2015*

**math**

no, the price depends on the other factors. All of the others are independent, since they can vary on their own.
*August 16, 2015*

**trigonometry**

Draw a diagram. If the pole has height h, then h = 21/(cot58°-cot67°) = 104.8 The two wires have length 104.8 csc67° = 113.9 104.8 csc58° = 123.6
*August 16, 2015*

**physics**

(a)since time=distance/speed, you have total distance: 73.2+73.2=146.4m total time: 73.2/1.2 + 73.2/3.1 = 84.6s avg speed: 146.4m/84.6s = 1.73 m/s do (b) the same way
*August 16, 2015*

**math**

to avoid having to use Greek letters, I'll just use x. I think you mean z = cos(x) + j sin(x) De Moivre's formula says that z^n + 1/z^n = z^n + z^-n = cos(nx) + j sin(nx) + cos(-nx) + j sin(-nx) = cos(nx) + j sin(nx) + cos(nx) - j sin(nx) = 2cos(nx) cos(x) is a ...
*August 16, 2015*

**Algebra**

x^2 * x^n x^(2+n) x^3 * x^n = x^(3+n) now, after the division, subtracting powers, you have x^((2+n)-(3+n)) = x^-1 = 1/x You can see that this is so, because in the original fraction, you can cancel the x^n factors, leaving just x^2/x^3 = 1/x
*August 15, 2015*

**Algebra**

better is |x-(-10)| >= 6 or |x+10| >= 6
*August 15, 2015*

**Algebra**

this is the sum of two cubes: (x^n)^3 + (y^n)^3 (x^n + y^n)(x^2n - x^n y^n + y^2n)
*August 15, 2015*

**Calculus**

1/(x+2) - 1/2 = (2-(x+2)) / 2(x+2) = -x/(2(x+2)) Now divide that by x, and you are left with -1/(2(x+2)) -> -1/4 You can divide by x, because until you take the limit, x is not zero.
*August 15, 2015*

**Algebra**

x^3 (3)(x^2+1)^2 (2x)+(x^2+1)^3 (3x^2) 6x^4(x^2+1)^2 + 3x^2(x^2+1)^3 3x^2(x^2+1)^2 (2x^2+x^2+1) 3x^2(x^2+1)^2 (3x^2+1)
*August 15, 2015*

**Algebra**

x^4(4) (2x+1)^3 (2x)+(2x+1)^4 (4x^3) Collecting factors, we have 8x^5(2x+1)^3 + 4x^3(2x+1)^4 = 4x^3(2x+1)^3 (2x^2+2x+1)
*August 15, 2015*

**Alg 2**

Just use the coefficients of Pascal's Triangle, and plug and chug: ((6-a)x)^12 + 12((6-a)x)^11(ay) + ... See it in all its glory at http://www.wolframalpha.com/input/?i=[%286-a%29x%2Bay]^12 This is one of those problems that are really pointless. Asking for the 12th power ...
*August 15, 2015*

**Alg 2**

r^3 = (1/5)/25 = 1/125 so, r = 1/5 An = 5*(1/5)^(n-1) = 125/5^n S8 = 25(1 - (1/5)^8)/(1 - 1/5) = 97656/3125
*August 15, 2015*

**Math**

a1 = 2 a2 = 3a1-1 = 3*2-1 = 5 a3 = 3a2-1 = 3*5-1 = 14 and so on
*August 15, 2015*

**Math Check**

proof by induction
*August 15, 2015*

**Math Check**

A little research will turn up many proofs that A(n) = n(n+1)/2 One easy way is to divide the numbers into pairs, from both ends. 1,n 2,n-1 3,n-2 ... Each pair adds up to n+1 There are n/2 such pairs. The result follows.
*August 15, 2015*

**Biology**

thank you
*August 15, 2015*

**Biology**

How is a protein different from a complex carbohydrate? a.The monomers that make up a protein vary whereas the monomers that make up a complex carbohydrate are all the same. b.Proteins function as energy storage polymers whereas complex carbohydrates function to control rates ...
*August 15, 2015*

**Math**

no idea. What shape is the container? Do the marbles touch all of the nearest sides of the container? Only one side? Any sides at all? Lots of specifics left out here.
*August 15, 2015*

**pre-algebra**

4/5 x + 5 < -3 4/5 x < -8 4x < -40 x < -10
*August 15, 2015*

**math**

clearly the black tea is 1/4 of the total The price p is thus 10(2.40)+30(3.20) = 40p
*August 15, 2015*

**lasmocol**

figure the number of moles of the silver compound. Since 500cm^3 is 0.5 liters, the molarity is twice the # of moles.
*August 15, 2015*

**Urgent math**

the expansion of (a+b)^10 starts out with a^10, so the term with a^3 is C(10,7)a^3b^7 So, since you have a = 3x and b = -3, that would be C(10,7)(3x)^3(-3)^7 = 360(27x^3)(-2187) = -7085880x^3
*August 15, 2015*

**Urgent math**

the common difference is d=5 So, the nth term is 4 + 5(n-1) or, 5n-1
*August 15, 2015*

**Algebra ASAP**

an = 0.85 * 1.29^n Now just plug in n=6
*August 15, 2015*

**Math**

No way to tell. What size cake did those ingredients make?
*August 14, 2015*

**AHOOOGAAH! HOMEWORK DUMP!**

So many questions! So little work to show! This is what is affectionately known as a Homework Dump.
*August 14, 2015*

**Algebra 1**

If 5% is gone, that leaves 95% of the previous population. So, #3.
*August 14, 2015*

**Algebra 1 - eh?**

eh?
*August 14, 2015*

**math**

(x+y)(x-y) = 105 Since 105 = 3*5*7, I suspect that x-y is one of those values. Now, 105 = 3*35 or 5*21 or 7*15 So, we can try x-y=3 x+y=35 (x,y) = (19,16) x-y=5 x+y=21 (x,y) = (13,8) x-y=7 x+y=15 (x,y) = (11,4)
*August 14, 2015*

**Geometry**

Wouldn't it be x-30+x+76=180 2x+46=180 2x=134 x=67 thus 67-30=37 and 67+76=143
*August 14, 2015*

**Geometry**

<1 &<2 are a linear pair. m<1=x-30 & m<2=x=76. Find the measure of each angle.
*August 14, 2015*

**Geometry**

That would makem it 24 + 34 =58 T NMO = 6(24)-28 58 + nmo = 144 - 28 = 119 116- 58 = 58 Thank you
*August 14, 2015*

**Geometry**

Line MO bisects <LMN, m<LMN =6x-28,m<LMO=x+34. Find m<NMO
*August 14, 2015*

**Math**

4/3 the speed means 3/4 the time. time = distance/speed
*August 14, 2015*

**math**

starting with x, .05x on rent, leaving .95x .95x * .20 = .19x on car, leaving .76x of the remainder, 7/20 = 4907, so 13/20 = 9113 So, 9113+4907 = .76x x = 18447.37
*August 14, 2015*

**Geometry**

since BD bisects the angle, we must have] 5x = 3x+10 2x = 10 x = 5 So, you are correct, but that does not answer the question: What is <ABC?
*August 14, 2015*

**Geometry**

sorry = my answer is 5
*August 14, 2015*

**Geometry**

Find the,<ABC if the line BD bisects <ABC and given m<ABD = 5x and m<DBC = 3x + 10.
*August 14, 2015*

**math**

since time=distance/speed, x/5 + 1/2 + x/(5/2) = 4 x = 35/6 His total distance is 2x
*August 14, 2015*

**math**

net inflow is 4 - 1/2 = 7/2 gal/min So, it takes 50/(7/2) = 14.3 min to fill
*August 14, 2015*

**Calculus**

Since x has degree less than x^2-100, the horizontal asymptote is y=0 since x^2-100 = 0 at x = ±10, and x≠0, those are the vertical asymptotes I find the function unrealistic. It implies negative concentrations, going off the charts as time increases. I suspect a ...
*August 14, 2015*

**Math**

x - x/5 - 2x/3 = 60 x(1 - 1/5 - 2/3) = 60 x(15-3-10)/15 = 60 x(2/15) = 60 x = 60(15/2) = 450
*August 14, 2015*

**college algebra**

Assuming you mean 3^(1-x) = 1/27 3^(1-x) = 3^(-3) 1-x = -3 x = 4
*August 14, 2015*

**algebra 2**

1st digit: 1-9 other digits: 0-9 So, 9*10*10*10 = 9000 possibilities
*August 14, 2015*

**Algebra ASAP**

find r by dividing any term by the previous term: r = 9/36 = 1/4 So, Tn = 36*(1/4)^(n-1) = 144/4^n T10 = 144/4^10 This was pretty straightforward. Looks like you need to review the topic.
*August 14, 2015*

**Algebra**

If the shorter list has x items, then x + x+7 = 33
*August 13, 2015*

**algebra**

5ac+10ab-25ad = 5a(c+2b-5d) 4x(a+b)-3y(a+b) = (4x-3y)(a+b) ax-bx+2a-2b = x(a-b)+2(a-b) = (x+2)(a-b) 2(x+y)-t(x+y) = (2-t)(x+y) These are pretty straightforward. Look how they worked out, and try some more on your own. It just takes a little practice to get used to seeing the ...
*August 13, 2015*

**physics**

see related questions below.
*August 13, 2015*

**calc**

clearly that would be ∫[0,2] t^2-1 dt = 2/3 But that is the algebraic distance (final displacement), since it starts out with negative velocity. To get the actual distance traveled, you need to separate the two parts: ∫[0,1] -(t^2-1) dt + ∫[1,2] t^2-1 dt = 2/...
*August 13, 2015*

**Math**

you are correct.
*August 13, 2015*

**Math**

Looks like you need to study what 50% more efficient means. It means B can do 50% more work than A in a given time. 50% = 0.5 So, 50% more means 1.5 times as much. That's 3/2. Think about it. If I do twice as much as you, it takes half (1/2) as long. If I do 3/2 as much as...
*August 13, 2015*

**Math**

3/2 as productive means it takes 2/3 as much time. So, (D).
*August 13, 2015*

**Math**

-4 = 0-4, but -1 ≠ 5-4
*August 13, 2015*

**Math**

Doesn't look like it, assuming I have read your garbled text correctly.
*August 13, 2015*

**Math Urgent**

well, let's see what happens. 12 6 3 10 5 16 8 4 2 1 4 2 1 4 2 1 tarting with T8, they repeat with a period of 3 1000 = 7+993 = 7+3*331 So, T1000 = 1
*August 13, 2015*

**STATISTICS**

looks like 0.12^3 to me.
*August 13, 2015*

**Math Probability**

clearly one step will take the ant to the equator of the octahedron. From there, there are 4 ways to go, only one of which continues on to the bottom. So, p = 1/4
*August 13, 2015*

**English**

thank you
*August 13, 2015*

**English**

Id the 2 adjectives. Argyles are patterned socks named after a Scottish clan. My answer patterned & Scottish
*August 13, 2015*

**Sociology**

thank you
*August 13, 2015*

**Sociology**

Understanding what is required to test theories? a- reason b- imagination c- validity research my answer is d
*August 13, 2015*

**math**

(6*42)/36 = 7
*August 13, 2015*

**Applied Geometry**

The area of an equilateral triangle with sides of 3 is 1/4 * 3^2 * √3 So, the volume of the pyramid is 1/3 (9√3/4)(4) = 3√3 = 5.2 You are correct.
*August 13, 2015*

**Geometry**

Nope. The whole circumference is 2πr = 16π
*August 13, 2015*

**Maths**

ok. now what?
*August 13, 2015*

**Maths**

do you mean 4√(132/143) - 2 or ∜(132/143) - 2 Not sure what "by" means here. Either way, there's not much that can be simplified. 132/143 = 11*12 / 11*13 = 12/13
*August 13, 2015*

**maths**

s/3 + 3t/4 = 30.5 2t = 6(j-s) j=34 solve that and you have s=24 t=30
*August 13, 2015*

**Math**

Just write down in symbols what they told you. If there are a apples and p pears, then a+p = 450 (1/2)a + (3/4)p = 265 a=290 p=160 a-p = 130
*August 13, 2015*

**math**

Which ways can two of the 15 coupons total $10? 2+8 5+5 8+2 P(2,8) = 5/15 * 2/14 = 1/21 P(5,5) = 2/15 * 1/14 = 1/105 P(8,2) = 2/15 * 5/14 = 1/21 Add up the ways and you get 11/105
*August 13, 2015*

**math**

20*15*6.00 = ?
*August 13, 2015*

**Arithmetic progession**

a+2d = 10(a+d) a+6d = 7a Solve for a and d, and then you can find the sum of T8+T15 = (a+7d)+(a+14d)
*August 13, 2015*

**MATH**

well, since there are 360° for 24 hours, every hour is 15° of longitude. The latitude does not matter.
*August 13, 2015*

**Urgent math**

well, finding the first six terms is easy, right? An = 5n^2-1, so here's a table: n An 1 5*1^2-1 = 5-1 = 4 2 5*2^2-2 = 20-2 = 18 3 5*3^2-3 = 45-3 = 42 4 5*4^2-4 = 80-4 = 76 5 5*5^2-5 = 125-5 = 120 6 5*6^2-6 = 180-6 = 174 Now just add 'em up to get S6
*August 12, 2015*

**Calculus**

just to get rid of pesky decimals. Fractions are exact; decimals can often be only an approximation, as in 2/3 = 0.666...
*August 12, 2015*

**Math**

If there were c correct answers, then there were 10-c wrong answers. So, now use her score to find c: 5c - 2(10-c) = 29
*August 12, 2015*

**Math (Calculus)**

you need both the product rule and the chain rule. f(x) = (3x)(x^2+4)^-1 f'(x) = (3)(x^2+4)^-1 + (3x)(-1)(x^2+4)^-2(2x) = 3/(x^2+4) - 6x^2/(x^2+4)^2 = (3(x^2+4)-6x^2)/(x^2+4)^2 = (12-3x^2)/(x^2+4)^2 The quotient rule produces the same result; in fact, you can see the ...
*August 12, 2015*

**math**

time of truck: 15:24-12:00 = 204 minutes time of flight: 3:24-1:48 = 96 minutes So, if the truck's speed was x km/hr, we have (x km/hr)(204 min) = (170 km/hr)(96 min) x = 170*96/204 = 80 You could convert everything to m/s, or use fractional hours or something, but if you ...
*August 12, 2015*

**Math**

If you google images for "ruler" you will find many images. Some have an inch divided into 16 parts, and some into only 8 parts. If you remember that 1/8 = 2/16, you should have no trouble getting what you want.
*August 12, 2015*

**Geometry**

If BC=2y and CD=2x, note that triangles ADF, ECF, and ABE are all right triangles with one leg half of a side of the rectangle. We know that ABCD has area (2x)(2y) = 72, so xy=18. ADF has area (2y)(x)/2 = xy = 18 ECF has area (y)(x)/2 = xy/2 = 9 ABE has area (y)(2x)/2 = xy = ...
*August 12, 2015*

**Algebra**

If there were c correct answers, then there were 10-c wrong answers. So, now use her score to find c: 5c - 2(10-c) = 29
*August 12, 2015*

**alegebra**

AP: T1 = a T3 = a+2d T9 = a+8d GP: T1 = a T2 = ar T3 = ar^2 a+6d = 14 a+2d = ar a+8d = ar^2 Solve all that and you find a=2 d=2 r=3 T20 of the AP is 2+19*2 = 40 Check: AP: 2 4 6 8 10 12 14 16 18 20 ... GP: 2 6 18 ...
*August 12, 2015*

**Algebra 2**

You know that y=5x+2 has slope 5. Now just use the point-slope form of the line: y+3 = 5(x-1) You can massage that into one of your choices, if it's not already there.
*August 12, 2015*

**Algebra ASAP**

P: 3^(2n)-1 is a multiple of 8 P(1): 3^2-1 = 8. True Assume P(k). Then with n=k+1, we have 3^(2(k+1))-1 = 3^(2k+2) = 3^(2k)*9 - 1 = 3^(2k)*8 + 3^(2k) - 1 but, we know that 3^(2k)-1 is a multiple of 8, say, 8m. Then we have =8(3^(2k))+8m = 8(3^(2k)+m) which is a multiple of 8. ...
*August 12, 2015*

**pre-cal**

The term containing x^k in (x+z)^n is C(n,n-k)x^(n-k)z^k. So, we have C(10,5)(x^5)(2y)^5 = 8064 x^5 y^5
*August 12, 2015*