Friday

August 28, 2015
Total # Posts: 33,101

**Algebra**

yes. commutative property of multiplication There is also a commutative property of addition, which could be written as (2 + p)(r + 9) = (p + 2)(9 + r)
*August 19, 2015*

**Algebra II**

transitive relates 3 values: a=b and b=c ==> a=c Clearly this is just a case of substituting z for y, since y=z.
*August 19, 2015*

**maths**

since r is constant, (1-t)/(2-5t) = (t+1)/(1-t) Solve that for t, and you will find that matching sequences are, with r=2 and r=1/3, 1/3, 2/3, 4/3, ... 9/2, 3/2, 1/2, ...
*August 19, 2015*

**physics**

Vy = 300-9.8t Vx = 519.6 So, at t=2, Vy = 280.4 Vx = 519.6 |v| = √(280.4^2+519.6^2) = 590.4 θ = arctan(280.4/519.6) = 28.4°
*August 19, 2015*

**Physics**

1.07 E = <1.07,0> .533 S = <0,-0.533> 4.62 @ W50.1°N = <-2.963,3.644> add them all up and you have a final displacement of <-1.893,3.111> = 3.642 @ N31.3°W now you can figure the velocity
*August 19, 2015*

**Math**

you are correct.
*August 19, 2015*

**Math**

well, 1364 = 14*93 + 62 17765 = 27*646 + 323
*August 19, 2015*

**math**

y = 3(x-2)^2+3 y' = 6(x-2) y" = 6 critical point is at x=2 minimum because y" > 0 there. http://www.wolframalpha.com/input/?i=3%28x-2%29^2%2B3 But then, you knew all that from Algebra I, right? Vertex of a parabola and all that.
*August 19, 2015*

**math**

the domain of rational functions is all reals except where the denominator is zero. x^2+8x+15 = (x+3)(x+5) So, I guess you can work it from there, right?
*August 19, 2015*

**math**

If you mean 10sin((x/4)-4π)-5 then that is 10sin((x-16π)/4)-5 period = 2π/(1/4) = 8π shift = 16π
*August 19, 2015*

**Algebra**

both right. good work. Of course, your nearest calculator could have confirmed your results...
*August 19, 2015*

**Algebra**

10(q-3) + 25q = 1300
*August 18, 2015*

**Diff Calculus**

When the water is y meters deep, the surface has a length of 5y and a width of 5. So, its volume is v(y) = 25/2 y^2 dv/dt = 25y dy/dt Now plug in y=1 and dv/dt=0.1 to find dy/dt
*August 18, 2015*

**Math algebr**

Looks like A to me.
*August 18, 2015*

**Math dimensional anaylsis**

9yd/3hr * 3ft/yd * 1hr/60min = 27/180 = 3/20 ft/min
*August 18, 2015*

**algebra**

just replace any x with -1, then simplify: 3(-1)^2-7 3*1-7 6-7 -1 you are correct
*August 18, 2015*

**Calculus**

you can always check your answers at wolframalpha.com As you can see, you're way off. If h = 3e^u where u is a function of x, then h' = 3e^u du/dx = 3e^(sin(x+2)) * cos(x+2) http://www.wolframalpha.com/input/?i=derivative+3e^%28sin%28x%2B2%29%29
*August 18, 2015*

**Math**

clearly the lines intersect where 1/4 x = -1/4 x 1/2 x = 0 x = 0 so, y=0 Looks like B to me. You can easily check to see that none of the other points lies on either line.
*August 18, 2015*

**Math (Probability)**

there are 3 numbers less than 4. So, 3/x = 1/10 ...
*August 18, 2015*

**physics**

well, the momentum has changed from 1500*40 to 1500*50 How hard is that?
*August 18, 2015*

**Slope**

recall the sloe-intercept form of a line: y = mx+b where m is the slope. slope is defined as the change in y, divided by the change in x. Since y=6x+3, y changes by 6 whenever x changes by 1. For, consider y(x) = 6x+3 y(x+1) = 6(x+1)+3 = 6x+9 x has changed by 1, and y has ...
*August 18, 2015*

**Algebra**

if you add the two equations, the x's cancel out, and you have 6y = -12 y = -2 so, x=2. The book answer is wrong. (6,-6) fits the 2nd equation, but not the 1st. If the 1st equation were -4x-2y = -12 then (6,-6) would be correct. So, it appears that the problem has a typo.
*August 18, 2015*

**math sqrt root**

x√2x + 2√2x^3 + 2x^2/√2x = x√2x + 2x√2x + x√2x = 4x√2x 2√(2x^3) = √((2x)(x^2)) = 2x√(2x) (2x^2)/√(2x) = = x√(2x)√(2x)/√(2x) = x√2x √(2/3) = √2/√3 = √2/√3...
*August 18, 2015*

**Math (Calculus)**

since 3 radians is in QII, sin is positive, and cos is negative. 3 is almost pi: 171.9 degrees
*August 18, 2015*

**Algebra**

vertical asymptote is ok horizontal asymptote is at y=1/3 (x^2+2)/(3x^2-5) = (1 + 2/x^2) / (3 - 5/x^2) as x gets huge, the fractions vanish, and we are left with 1/3 When the degree of top and bottom are the same, then the limit is the ratio of the coefficients of the highest ...
*August 18, 2015*

**math**

y = ax+bx^2 2a+4b = 14 5a+25b = 65 y = 3x+2x^2 take it.
*August 18, 2015*

**Lyncheez Bee (math)**

If the digits are xyz, then x+y+z=9 2y=x+z 2x=z The number is thus 234
*August 18, 2015*

**maths**

n=2k+1, so clearly n must be odd. Now, it is also 5k+4, so k must be odd since otherwise 5k is even, and so is n. Any odd multiple of 5 ends in 5, so n must end in 9.
*August 18, 2015*

**maths**

2400 is a multiple of 3, so y5 must be a multiple of 3. Can you think of any 2-digit multiples of 3 ending in 5?
*August 18, 2015*

**Algebra**

I can see the (a^3)^(1/4) in the denominator, but there's no way to get 648 in the top from what you have written.
*August 18, 2015*

**maths**

Do you mean a 4-digit number 91z5? The digits of any multiple of 9 add up to a multiple of 9. So, 9+1+z+5 = 15+z So, z=3 to make the sum 18. 9135 = 9*1015
*August 18, 2015*

**maths**

1.94 x 10^2 Not sure just what you're looking for.
*August 18, 2015*

**pre-cal**

Remember the law of sines? a/sinA = b/sinB 24/sin42° = b/sin87° Now you can find b with no trouble.
*August 18, 2015*

**maths**

Doing my best to parse the wordy and ambiguous notation, I get ((4/3)√3 - 2√2+3)/(3√3 + 2√2) No, that is too weird. How about 4/(3√3-2√2) + 3/(3√3+2√2) Now we can make a common denominator of (3√3-2√2)(3√3+2&#...
*August 18, 2015*

**Math**

If x gallons were poured, then (35+x)/(4.5+x) = 7/2 x = 7.7 Now it's easy peasy.
*August 18, 2015*

**algebra**

r^3 = 3/192 = 1/64 r = 1/4 So, use that to find x and y Or, you can say (x/192)^2 = 3/x x=48 y/48 = 3/y y=12
*August 18, 2015*

**Math**

rev/hr = rev/min * 60min/hr L/rev = L/hr * hr/rev = (L/hr)/(rev/hr) mL/rev = L/rev * 1000mL/L
*August 18, 2015*

**calculus**

min/max occur where y'=0 So, just solve 4x^3-12x^2+8x=0 So, which are min and which max? Minimum if y" > 0 (concave up) Maximum if y" < 0 (concave down) So, take a look at y" = 4(3x^2-6x+2)
*August 18, 2015*

**math 5**

I didn't see a question, but your response seems like a reasonable answer.
*August 18, 2015*

**Math**

R=xxx clearly the 1st digit is 0 or 5, so it must be 5, since 3-digit numbers don't usually start with 0. R=1x5 The second and third digits add to 8 R=135 The last item is redundant.
*August 18, 2015*

**maths - incomplete**

did you forget the interest rate? The principal?
*August 17, 2015*

**Algebra**

That would be ∜(8/9a^3) Not sure what you mean by simplify. You could break it into separate factors, but There aren't any 4th-powers to factor out of the radical.
*August 17, 2015*

**math**

The angles are 5x,6x,7x and they add to 180. So, 18x = 180, x=10, and the angles are 50,60,70 So what do you think?
*August 17, 2015*

**math**

check your distance formula. It is √((5-(-3))^2+(-5-1)^2) = √(8^2+6^2) = √100 = 10
*August 17, 2015*

**math grade 12**

.75 * .75
*August 17, 2015*

**math grade 12**

Add up all the points. You need x where 85+89+x >= 3*90
*August 17, 2015*

**Math**

much better!
*August 17, 2015*

**Math**

How ever did you come up with that answer? You have 5a, and you want a by itself. How do you get rid of the 5? Recall that 5/5 = 1
*August 17, 2015*

**Math using symbols**

you are correct on both of them. Good work.
*August 17, 2015*

**Math using symbols**

you have 2 rows, each with 3+4 stars So, what do you think? Hint: distributive property In #2, there is no multiplication, just 3+4+5 stars So, what do you think? Hint: associative property
*August 17, 2015*

**Math**

Nope. Inequalities do not have a single value for a solution. -3 < 2x+1 < 5 -4 < 2x < 4 -2 < x < 2 Clearly 4 does not work. 2*4+1 is not less than 5. Any value between -2 and 2 will work.
*August 17, 2015*

**Math**

so am I. All I can do is use what you wrote, which doesn't make a lot of sense to me. How about you try posting the real question? |1| = 1 |11| = 11 Other than that, I have no help to give at this point.
*August 17, 2015*

**Math**

That would be _____+10
*August 17, 2015*

**algebra 2**

If you are trying to find the determinant such that |0 0 -1| |3 x 0| = x^2 |2 0 3| Then that reduces to 2x = x^2
*August 17, 2015*

**math help**

It is C if you meant 5*2x^2 Try not to confuse x (the variable) with x (multiplication) Use * to multiply ^ for powers
*August 17, 2015*

**Algebra**

domain is all reals except where the denominator is zero So, if you have 1/(x-1)^2 - 5 D= all reals except x=1 Clearly, 1/(x-1)^2 is smallest when x is huge. Then it is close to zero, but always a little bit positive. So, R= all reals y > -5
*August 17, 2015*

**Algebra**

If there are x vials of A, then then the rest (60-x) are of B. So, adding up the costs, we have 39.95x + 30.34(60-x) = 2022.21 Now just solve for x and then figure 60-x.
*August 17, 2015*

**kogi state university**

If there are n to choose from, then that is P(n,5) or C(n,5)
*August 17, 2015*

**math**

168 @ 43.5° = <115.6,121.9> 33 @ 133.5° = <23.94,-22.72> add up the x- and y-components and the resultant velocity is <139.54,99.18> = 171.20 @ 54.6°
*August 17, 2015*

**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*