Tuesday

September 27, 2016
Total # Posts: 44,116

**calculus**

u • v × w is just the determinant |5 9 -6| |5 8 -1| |-2 8 3|

*August 30, 2016*

**Math**

5/6 * 36 / 4

*August 30, 2016*

**That's for sure**

first cos(z) is never greater than 1. Second, z! is defined only for integers.

*August 30, 2016*

**Math**

well, 8012 = 4*2003 now just keep going

*August 29, 2016*

**Pre-Calculus**

distance = d rt = (3/4 r)(t+12) rt = 3/4 rt + 9r 1/4 rt = 9r t = 36 So, it takes 36+12=48 minutes to bike home

*August 29, 2016*

**algebra**

not quite. You want d to be between those values: 4.999 <= d <= 5.001

*August 29, 2016*

**algebra**

|d-5.000| <= 0.001

*August 29, 2016*

**Geometry**

how is 30.0 to the nearest 0.0001? Maybe you meant nearest 0.0001m, not mm?

*August 29, 2016*

**math**

when all you have is $100 bills, you gotta round to hundreds.

*August 29, 2016*

**Math**

I vote for 3^4^5 ≈ 10^488

*August 29, 2016*

**Math**

clear fractions, or cross-multiply 3(5x+6) = 7(3x-9) 15x+18 = 21x-63 ...

*August 29, 2016*

**algebra**

2x-4 = 22 2x = 26 x = 13 same way for the other

*August 29, 2016*

**Math**

P(q) = 1/3 P(n|d,q) = 2/9 P(n|d,n|d) = 4/9 So, what do you think? the 1st probability means that if the 1st coin is a quarter, the 2nd does not matter.

*August 29, 2016*

**geometry**

tb = tu+ub -3 = 1-x + 4x+17 Now just find x, and then tu. not sure how you get negative lengths.

*August 29, 2016*

**algebra**

m = g+150 2(m-190) = g Now just solve for m.

*August 29, 2016*

**Math**

just plug in x = -2 y(-2) = 2(-2)^2 + 8(-2) + 5 = 2*4 - 16 + 5 = 8-16+5 = -3 If y is a function of x, y(2) means evaluate y at x = -2, not multiply y by -2. Looks like you have some serious reviewing to do.

*August 29, 2016*

**Math**

recall that the vertex is at x = -b/2a In this case, that is at x = -8/4 = -2. y(-2) = -3 So, the vertex is at (-2,-3) You can also determine this by completing the square: y = 2x^2 + 8x + 5 = 2(x^2 + 4x + 4) - 3 = 2(x+2)^2 - 3 New recall that the vertex of y = a(x-h)^2 + k is...

*August 29, 2016*

**PHYSICS**

see related questions below

*August 29, 2016*

**Math**

solve as if they were equations. The lines intersect at (-1/3, 4/3) The solution is the area to the right of x = -1/3, below the blue line and above the red line. see http://www.wolframalpha.com/input/?i=plot+y+%3D+2x%2B2,+y+%3D+-x%2B1

*August 29, 2016*

**Math**

Since all the numbers on the left are even, I can't see how to get an odd result.

*August 29, 2016*

**Algebra2**

If you want to reflect the whole graph across the x-axis, that would be -(x^2+5) = -x^2-5 Make a visit to wolframalpha.com and type in your functions. It will show the graph. Make a change a refresh, and you can see the new graph. You can do more than one at a time by ...

*August 29, 2016*

**Algebra2**

Let g(x) be the reflection of f(x)=x^2+5 What is the function rule for g(x)? I know the first part would be-x^2 but not sure if the 2nd part is a plus or minus.

*August 29, 2016*

**Algebra2**

thank you

*August 29, 2016*

**Algebra2**

Write an equation for the following transformation of y=x: a vertical stretch by a factor of 6. A. y=6x B.y=x/6 C.y=x+6 D.y=x-6 my answer is a

*August 29, 2016*

**Algebra2**

yes, because the +y axis is up

*August 29, 2016*

**Algebra2**

Thank you so the +5 number would always be up and a -5 number would always be down?

*August 29, 2016*

**Algebra2**

stretch vertically by 5: -35x^2 shift up 5: -35x^2 + 5

*August 29, 2016*

**Algebra2**

What transformations change the graph of (f)x to the graph of g(x)? f(x) = -7x² ; g(x) = -35x²+5

*August 29, 2016*

**Math**

If you mean effort then you are right. Maybe some of that effort should go into spelling, typing, or proofreading...

*August 29, 2016*

**math**

75% is 3/4 so, 1/4 failed so, what is 1/4 of 36?

*August 29, 2016*

**phisics**

After t hours, the total distance is covered, so 7.8t+7.6t = 6.0+4.2 t = 0.662 hr So, A's final position after that long is -6 + 7.8 * 0.662 = -0.836 km or, 836 meters west of the pole.

*August 29, 2016*

**math**

the perimeter is half a circle plus the diameter, so 3π+6 assuming the shaded shape is the semicircle. If not, I'm sure you can work it out.

*August 29, 2016*

**physics**

density = mass/volume, so (6×10^3 kg) / (4π/3 * (6.4×10^3 km)^3) If you do the division, you will see an unexpectedly small result You sure the mass of the earth is only 6 metric tons?

*August 29, 2016*

**Maths**

well, you know that 2x(3x-4) = 6x^2-8x (x-1)(x+3) = x^2+2x-3 now just subtract

*August 29, 2016*

**Math**

correct

*August 29, 2016*

**Math**

If I gave you $2 each hour, how long would it take for you to have $8? Same problem, but using positive numbers.

*August 29, 2016*

**Math**

differences: 10,10,10,10 looks like an AP to me.

*August 29, 2016*

**physics**

not sure what "four folded" means. If you mean the cross-section area is multiplied by 4, then the resistance is divided by 4. If the diameter is multiplied by 4, then the resistance is divided by 16 If the length is multiplied by 4, then also the resistance.

*August 29, 2016*

**mathematics**

AP/AB = 2/3 (AP+2)/AB = 3/4 (AP+2)/AP = 9/8 1 + 2/AP = 9/8 2/AP = 1/8 AP = 16 16/AB = 2/3 18/AB = 3/4 AB = 24

*August 29, 2016*

**Math**

If the two numbers are x and y, then y = 3x-1 2x+y = y+18 Now just solve for x and y

*August 29, 2016*

**math**

assuming you meant "tens digit" then you might have 123 124 ... 689 789

*August 29, 2016*

**math**

2/3 + (1/2)(1/3) = 5/6 So, 1/6 of the original number is 6

*August 29, 2016*

**radical equation please help!!!**

If you're trying to solve the equation, √(1+x) - √(1-x) = √(1-x-√(1+x)) (√(1+x) - √(1-x)) = √(1-x-√(1+x))^2 (1+x) - 2√(1-x^2) + (1-x) = 1-x-√(1+x) 2 - 2√(1-x^2) = 1-x-√(1+x) 1+x = 2√(1-x^2)-&#...

*August 29, 2016*

**math help please?!**

minors and cofactors are simple; just follow the rules. I'll do the ones for [1;1] minor: remove row 1 and column 1: [-2 6] [3 -6] cofactor: add the index of the row and column, and use that as an exponent of -1, then multiply the minor by that: (-1)^(1+1) = (-1)^2 = 1 so...

*August 29, 2016*

**Math**

oops. du = -5cos^4x sinx dx things are a bit more complicated than I showed here, since you wind up with a sin^2(x), which has to be converted into (1-cos^2 x) and you go around again.

*August 29, 2016*

**Math**

∫(cos^3 x)^2 dx = ∫cos^6 x dx Now, just as cos(6x) can be expanded into a polynomial in cos(x), cos^6(x) can be expanded into a sum of cosines of multiple angles: = ∫(1/32)(15cos(2x)+8cos(4x)+cos(6x)+10) dx = 1/32 (15/2 sin(2x) + 2sin(4x) + 1/6 ...

*August 29, 2016*

**Math**

Let x,y,z be the amounts of the three, in the order named. Then x+y+z = 24 x+z = 2y y+z = x Now solve for x. Hint: it is not 21

*August 29, 2016*

**Physics**

a = 50kph/8s = 25/4 km/hr/s = 1.736 m/s^2 Vo = 40 km/hr = 11.11 m/s, so s = Vo*t + a/2 t^2 now just plug in the values for Vo,a,t

*August 29, 2016*

**applied maths**

Draw a diagram of the box with the sides unfolded and lying flat. Now draw a straight line from spider to fly, and the distance x is x^2 = (1/2)^2 + (3/2)^2

*August 29, 2016*

**Calculus**

see related questions below

*August 29, 2016*

**math**

each ate 3/8 so, 5/8 remained

*August 29, 2016*

**math**

Many choices: 3/5 4/6 5/7 ... didn't you even try at all?

*August 29, 2016*

**science**

Its name?

*August 28, 2016*

**Math**

If Matt takes m hours, then Carla takes 4m. So, together, 1/m + 1/4m = 1/8 5/4m = 1/8 m = 10

*August 28, 2016*

**Math science**

end of what? zero is just a number, like any other. Though it does have several unique properties. There is no "end" number.

*August 28, 2016*

**Urgent Math**

I like it! But the half-angle formula would have gone directly to (cos2x - 1)/sin2x = -tanx Then we'd have ∫tan^2(x) dx = ∫sec^2(x)-1 dx = tanx - x + C

*August 28, 2016*

**Urgent Math**

∫(cot2x-csc2x)^2 dx ∫ cot^2(2x) - 2cot(2x)csc(2x) + csc^2(2x) dx ∫ 2csc^2(2x) - 1 - 2cos(2x)/sin^2(2x) dx Now everything is standard forms, so you get -cot(2x) - x + 1/sin(2x) csc(2x) - cot(2x) - x or, you can go on to get (1-cos(2x))/sin(2x) - x (1 - 2cos^2(...

*August 28, 2016*

**physics**

the height is modeled by the function h(t) = 60 + 30t - 4.9t^2 max height is at the vertex of the parabola, at t = -b/2a = 30/9.8 Use that to evaluate h(t) there. It hits the ground when the height has dropped to zero. So, just solve 60 + 30t - 4.9t^2 = 0

*August 28, 2016*

**physics**

while I did miss on the velocity/speed problem, I think we can assume that if he is driving east, as given, that is the direction of the straight road... But, it's fun to be picky when the problem is poorly stated.

*August 28, 2016*

**physics**

assuming (1) that you meant 48.0 km/hr (2) that speed was achieved during the 144km trip then since time = distance/speed, it would take 144/48 = 3 hours

*August 28, 2016*

**Math**

Just substitute in a desired value. f(x) = 3x+2 f(a) = 3a+2 f(2a) = 3(2a)+2 = 6a+2 f(4) = 3(4)+2 = 14 and so on

*August 28, 2016*

**Math**

A = x(3-2x) = 3x-2x^2 P is ok your conclusion is correct, except that 3-2x = -1 when x is 2.

*August 28, 2016*

**Math**

solve what? The only thing we can say is that the bearing of q from p is 180+55 = 235°

*August 28, 2016*

**math**

aside from noting that (x^3+y)^0 = 1 this is a simple exercise in expanding powers of binomials. Type in your expression at wolframalpha.com to verify your results. >wink wink< Be sure to use ^ for powers, or it will just multiply.

*August 28, 2016*

**College math**

just plug it into your formula: 10000(1 + .09/12)^(12*7)

*August 28, 2016*

**Trig**

Think of a 5-12-13 triangle. Draw the triangle and review your basic trig functions.

*August 28, 2016*

**Chemistry**

1 mole contains Avogadro's Number of K+ ions

*August 28, 2016*

**calcus**

Draw the base line AB of the triangle. Now construct the perpendicular bisector of AB. The vertex C can be anywhere up along that bisector to form an isosceles triangle.

*August 28, 2016*

**calcus**

Come on - just because you are making the triangle less tall does not mean that the base has to change. It is still isosceles. The only sticking point comes when the two legs shrink down to 1/2 the base length. At that point the triangle has flattened into a straight line.

*August 28, 2016*

**calcus**

If the leg length is s, the height of the triangle is h^2 + (10√3)^2 = s^2 or h^2 + 300 = s^2 The area is a = 1/2 bh = 10h√3 = 10√3 √(s^2-300) when the triangle is equilateral, s=20√3 da/dt = 10√3 s/√(s^2-300) ds/dt = 10√3 * 20&#...

*August 28, 2016*

**geometry**

just set the two expressions equal to each other: 4(x+2) = 2(3x+2) + 2(x-1) Now you can solve for x and then evaluate either expression for the perimeter.

*August 28, 2016*

**Bio physics chemistry pre medical**

the molar mass is 20*C+30*H+O where C,H,O are the atomic masses of the atoms. Now divide 500g/molarmass * Avogadro's Number review what moles are

*August 28, 2016*

**Math**

2(6+2) just the perimeter, in meters. Kind of boring, using 1m as the edge width.

*August 28, 2016*

**Math**

(30-2w)(20-2w) = 375

*August 28, 2016*

**Math**

v = π/4 d^2 h now use your numbers

*August 28, 2016*

**Math or Maths???**

prolly from mathematics -- "maths" retains the "s"

*August 28, 2016*

**maths**

Oops. I worked an A.P., not G.P. a = ar + 4 ar + ar^2 = "2 by 2/3" Now just solve for a and r and then list the first 4 terms.

*August 28, 2016*

**maths**

a = (a+d)+4 (a+d)+(a+2d) = "2 by 2/3" (whatever that means) Anyway, now just solve for a and d, and then list the first 4 terms.

*August 28, 2016*

**Math Need Help**

Just do a long division first: ((2x+4)(2x-1))/(3x-2) = 4x/3 + 26/9 + 16/9 * 1/(3x-2) so, ∫((2x+4)(2x-1))/(3x-2) dx = 2x^2/3 + 26/9 x + 16/27 log(3x-2) + C

*August 28, 2016*

**Maths**

If the 3rd side is x, then we must have 8-6 < x < 8+6

*August 28, 2016*

**math**

google is your friend. See http://www.mathopenref.com/coordtrianglearea.html

*August 28, 2016*

**percentage**

20% of (12000-2000) = 2000 30% of the remaining 10000 is 3000 so now you can see how much she saves monthly, and thus can figure the annual savings.

*August 28, 2016*

**Calculus**

Your typo does not help, but the problem is discussed here: http://math.stackexchange.com/questions/217026/show-that-f-has-at-most-one-fixed-point remember that google is your friend.

*August 28, 2016*

**Math College 115**

(7.5-6.5)/(2009-2004)

*August 28, 2016*

**math**

when you said quadrilateral, that means four sides.

*August 28, 2016*

**maths**

The two angles form a straight line, so how many degrees is that in total?

*August 28, 2016*

**Math**

well, let XY=2 and YZ=5 XY/XZ = 2/7

*August 27, 2016*

**College Math**

(4*50)/350 = 4/7 = 57%

*August 27, 2016*

**Math**

use either point in your equation: -3/13(-10)+b = 3 30 + 13b = 39 13b = 9 -3/13(-2)+b = -5 6+13b = -65 13b = -71 Hmmm. They should come out the same. Let's check your slope: m = (-5-3)/(-2+10) = -1 So, y = x+b -(-10)+b = 3 10+b = 3 b = -7 -(-2)+b = -5 2+b = -5 b = -7 So, ...

*August 27, 2016*

**Algebra 1**

how vewwy vewwy wude!

*August 27, 2016*

**Math**

differences: -1/3, 1, -3 ratios: 0, ∞, -2 since neither is constant, it is neither an A.P. or a G.P. So, how to figure the next terms? Note that the differences form a G.P., with the next terms 9,-27,81 Adding those to -2, we get 7,-20,61, or choice (A)

*August 27, 2016*

**Maths**

If you take the time to list the possible events qnd the contents of the jqr qfter eqch, the qnswer will become cleqr. qnnoying, isn't it?

*August 27, 2016*

**Maths**

2/3 * 2/3

*August 27, 2016*

**real analysis**

google is your friend http://math.stackexchange.com/questions/283987/interior-closure-and-boundary-of-the-sets-of-all-rational-and-irrational-number

*August 27, 2016*

**Higher Math**

tan10x = 2tan5x/(1-tan^2(5x)) so, 2tan(5x)/(1-tan^2(5x)) = 1/tan(5x) 2tan^2(5x) = 1-tan^2(5x) 3tan^2(5x) = 1 tan 5x = ±1/√3 Now use that to get your reference angles and produce as many solutions as your domain requires.

*August 27, 2016*

**Math**

height: h width: h+4 length: w+8 = h+12 h(h+4)(h+12) = 512 all the factors of 512 are powers of 2, so we have 2^9 = 512 2+3+4 = 9 2^2 * 2^3 * 2^4 = 512 4*8*16 = 512

*August 27, 2016*

**math**

when n=1, A1 = -7*1+8 = -7+8 = 1 now just start subtracting 7 again and again.

*August 27, 2016*

**math**

since you keep multiplying by -1, there will be (n-1) of them by the nth term.

*August 27, 2016*