Wednesday

October 14, 2015
Total # Posts: 34,616

**Physics**

speed: (130+65)m/(16.0+4.3)s = 9.61 m/s velocity: (130-65)m/(16.0+4.3)s = 3.20 m/s
*October 6, 2015*

**math**

well, Manny is now 18, so ...
*October 6, 2015*

**maths**

yadda yadda yadda. The equations say it all. The words are redundant. If runner 1 passes runner 2, their distances are equal: 0.2t(t-5.1)(t-9.1) = 2.4 + 0.75t t ≈ 10.1 Check out the graphs at http://www.wolframalpha.com/input/?i=0.2t%28t-5.1%29%28t-9.1%29+%3D+2.4+%2B+0.75t
*October 6, 2015*

**pre-cal**

since we have real coefficients, and 2i is a root, so is -2i. If 1/2 is a root, one factor of p(x) is (2x-1). So, p(x) = (2x-1)(x-2i)(x+2i) = (2x-1)(x^2+4)
*October 6, 2015*

**math**

recall the law of cosines, and you will see that θ can be found using 38^2 = 30^2 + 27^2 - 2(30)(27)cos(π-θ)
*October 6, 2015*

**Math**

well, you have 5*4 = 20 How many more to get 30?
*October 6, 2015*

**Algebra**

if they traveled x hours at 20 mi/hr, then they went (260-20x) miles at 70 mi/hr Since time = distance/speed, (260-20x)/70 + x = 9 x = 7.4 check: they traveled 1.6 hr * 70 mi/hr = 112 mi 7.4 hr * 20 mi/hr = 148 mi Total: 260 mi
*October 6, 2015*

**Calculus/Math**

you have (1-2x)/(√(1+x^2)-1) multiply top and bottom to get (1-2x)(√(1+x^2)+1) / (√(1+x^2)-1)(√(1+x^2)+1) = (1-2x)(√(1+x^2)+1)/x^2 = (1-2x+√(1+x^2)-2x√(1+x^2))/x^2 = 1/x^2 - 2/x + √(1/x^4+1/x^2) - 2√(1+1/x^2) as x→&#...
*October 6, 2015*

**MATH**

7(4z-3) > 59 28z - 21 = 59 28z > 80 z > 20/7
*October 6, 2015*

**jms**

exponents first
*October 5, 2015*

**Physics**

A+AB = A(1+B) = A(1) = A (A+B)(A+C) = A(A+C)+B(A+C) = A+AB+BC = A+BC
*October 5, 2015*

**Calculus 1**

well, just plug in some numbers! f(0) = 10, so a/(1+b) = 10 df/dt = a(0.5be^(-0.5t))/(1+be^-0.5t)^2, so a(b/2)/(1+b)^2 = 4 Solve those two equations, and you get a = 50 b = 4
*October 5, 2015*

**Geometry**

well, just draw angle ABC. Then pick a point D somewhere between B and C, and draw the ray BD. Then you have (7x-9)+(5x-6) = (5x+6) ABC is the big angle. ABD + DBC = ABC
*October 5, 2015*

**Algebra**

You want x where 0.046x + 0.10(6500-x) = 1000
*October 5, 2015*

**Combination and Permutation**

Clearly, that is 52C2 Doesn't matter whether the deck is shuffled or not. Same 52 cards!
*October 5, 2015*

**Math**

the two-point form of the line is y+5 = -9/4 x now just rearrange things as needed.
*October 5, 2015*

**Math**

well, just plug in the point: 3(-5)-3(6)+2 = -15-18+2 = -31 so, 3x-3y+2 = -31 3x-3y+33 = 0 x-y+11 = 0
*October 5, 2015*

**math**

use s = rθ
*October 5, 2015*

**geometry**

(-2,-1) -> (-2,-9) -> (4,-9)
*October 5, 2015*

**Geometry**

assuming that ABCDE are points in that order, draw the line and mark 'em off. AB=BC CD=DE AE = AB+BC+CD+DE = AB+AB+DE+DE = AB+AB+AB+AB = 4AB
*October 5, 2015*

**math**

just look up the formula for the area of a segment of radius r and angle θ: a = 1/2 r^2 (θ-sinθ) Now plug in r=3 and θ=π/3
*October 5, 2015*

**precalc**

32 cos 32°
*October 5, 2015*

**Math (Trig)**

I think you should apply the angle bisector theorem here, since AD bisects angle ABE and AE bisects angle ADC.
*October 5, 2015*

**Mathematics**

sorry. can't be done with elementary functions. Better use Newton's method or graph it and read the solution.
*October 5, 2015*

**geometry**

well, seems to me you just need to do the construction and try the step you think will work.
*October 5, 2015*

**Math**

It is in scientific notation. I guess standard form would be found by shifting the decimal point 5 places to the left: 0.0000356
*October 5, 2015*

**math algebra**

just keep track of all the costs involved: 1.80x + 2.60(20) = 2.12(x+20)
*October 5, 2015*

**8th grade geometry**

If your answer is correct, you made a typo in the 1st point of the problem. If two of the vertices are (3,-2) and (-3,-2) then the base is clearly a horizontal line. So, any point 3 units above the base will produce the desired height. That would be (x,1). (0,1) is the point ...
*October 5, 2015*

**Calculus**

As always, draw a diagram. Using similar triangles, the man's shadow height h when he is at a distance x from the light, is given by 2/x = h/12 or, hx = 24 So, when the man is 4m from the wall (8m from the light) 8h=24, h=3 x dh/dt + h dx/dt = 0 Now plug in your values: 8 ...
*October 5, 2015*

**Math in Science**

42
*October 5, 2015*

**math**

in years, d = j+3
*October 5, 2015*

**Math**

15x-20 <= 130 15x <= 150 x <= 10
*October 5, 2015*

**Algebra**

not sure what 2Ex<33 means, but it has something to do with integers less than 33.
*October 5, 2015*

**Pre Calculus**

#1 in a linear function, equal spacing in x produces equal spacing in y. The ratio is called the slope, and is constant. Only table #3 meets that condition. #2 A function whose domain is [2, infinity): √(x-2) An arithmetic sequence: 1,2,3,4,... A system of equations with...
*October 5, 2015*

**Geometry help**

it appears that angles 1 and 2 form a straight line, so their sum is 180°.
*October 5, 2015*

**Physics**

these all just use the Pythagorean Theorem, or the distance formula, which is the same. Just figure out the final location, and then use the formula. For #1, (0,0) -> (-10,0) -> (-10,-10) distance is √(10^2+10^2) = 14.1
*October 5, 2015*

**History**

Your parents own their own business and they do very well financially. They are very independent and take responsibility for all their own business and personal costs. based on this information which political party are your parents a member of? My answer is Republican Party
*October 5, 2015*

**Math help please?! :)**

(4x10^3)(6x10^6) = (4x6)x(10^3 x 10^6) = 24x10^9 but that is not SN. You need 2.4x10^10 profit is income less cost. In this case, since the same number of shares were bought and sold, just multiply 15 by the difference in prices: 15(20.375-14.875) = 15(5.50) = 82.50 because he...
*October 5, 2015*

**Geometry Check please**

since only multiplication was used, I'd say that's a good guess... Unless you like dividing by 1/2 ...
*October 5, 2015*

**Geometry Check please**

Answers are good. Typing, not so much . . .
*October 5, 2015*

**Math**

|n| is just the distance from n to zero. n can be to the left of 0 or to the right of 0. |-3| = 3 because -3 is 3 units away from zero. -3 is to the left of 0, +3 is to the right, but in either case. |-3| = |+3| = 3 Get out your number line and try plotting some points. And ...
*October 5, 2015*

**Math; PLEASE CHECK MY ANSWERS**

1C 2D ok 3 B and C are both greater. Typo? If you meant 5.5x10^7, then just B
*October 5, 2015*

**math, mechanics**

Well, if F is dU/dr, and U is a function of r, then there will certainly be r in the answer. But, you want F(r) at r=r0, so geez, just plug in r0! Am/r0^(m+1) - Bn/r0^(n+1) There are other ways of expressing that, but that's another exercise.
*October 5, 2015*

**math, mechanics**

still looking for what F is.
*October 5, 2015*

**History**

thank you
*October 5, 2015*

**History**

I think a
*October 5, 2015*

**History**

What is a key element of democracy? a- self-determination b- selfishness c- violent d- heredity My answer would be a or b
*October 5, 2015*

**math**

either (7/5 * 60) or (7/2 * 60) depending on who got the $60.
*October 5, 2015*

**Language Arts (- Ribbons -)**

∫C (2z-3)/[(z^2-4)(z+2)] dz
*October 5, 2015*

**Math**

this keeps cropping up. See the related questions below. But, just follow the rules you have learned: -12 / 3 * (-8 + (-4)^2 - 6 ) + 2 -12 / 3 * (-8 + 16 - 6 ) + 2 -12/3 * 2 + 2 -4 * 2 + 2 -8 + 2 -6
*October 5, 2015*

**Math**

since 3/4 * 1 = 3/4 3/4 * 4/3 = 1 multiplying 3/4 by any number between 1 and 4/3 will work. Or, a little more formally, 3/4 <= (3/4) x <= 1 1 <= x <= 4/3
*October 5, 2015*

**Math help**

If there are x bargain boxes and y deluxe boxes, you want to maximize p = 4x + 6y where 4x+9y <= 300 8x+3y <= 400 Now use your favorite solution method or tool, and you find max p when x=45 y=13 http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html is a nice tool. It ...
*October 5, 2015*

**Geometry**

reflection through the line y=x moves (x,y) -> (y,x) So, it looks like C with a typo. I mean, geez, did you try actually plotting a point and seeing what happened if you flipped it over the line y=x? or maybe googling reflections? http://www.regentsprep.org/regents/math/...
*October 5, 2015*

**MATH 115 PRE-ALGEBRA**

Just use the distributive property to get rid of the parentheses: 6(3m-7)-2(12y-5)+4(y+6) 6(3m)-6(7)-2(12y)-2(-5)+4(y)+4(6) 18m-42-24y+10+4y+24 Now you can use the commutative property to rearrange things: 18m-24y+4y-42+10+24 18m+y(-24+4)-8 18m-20y-8 If that m was really ...
*October 5, 2015*

**Math**

well, 2007 is 1990+17, so just plug in 17 for t.
*October 5, 2015*

**calculus**

well, you only have two points, so a line would suffice to join them. But, as the slope at the end of the ramp is not 90/120, that gives another constraint. That's like specifying a third point. So, use a quadratic to model the ramp. y = ax^2+bx+c y(0) = 100, so c=100 y(...
*October 5, 2015*

**maths**

how many cards? how many aces of hearts? so, P(A♥) = ...
*October 5, 2015*

**Algebra**

well, your equation, which is already in standard form, just needs a value for b. just plug in a point x-2y=b 4-2(-2) = b so, b=8 x-2y=8 which is standard form with a=1 b=-2 c=8
*October 5, 2015*

**Math**

think about it. The y-axis has equation x=0 so, any line parallel to the y-axis, say, c units away, will have the equation x = c Your point is (4,5), so the line you want is x = 4 Its slope is undefined, since x never changes. The line is vertical.
*October 5, 2015*

**trigonometry**

If you drop an altitude from C to AB, call it P, and if AP=x then BP = 125-x. Then the river's width is CP. Call that w. We then have w cotA + w cotB = 125 w = 125/(cotA+cotB) Now just plug in your values for A and B.
*October 4, 2015*

**Math**

I think A,C,D are all needed.
*October 4, 2015*

**math**

I don't believe that c(x) is correct as stated. It means that c(x) increases with time, not likely for a cooling piece of metal. So, either c(x) does not represent the metal's temperature after x hours, or it indicates how many degrees it has cooled. In either case, c(...
*October 4, 2015*

**Physics**

well, the vertical position (in meters) of the spider at time t is y(t) = 0.890 sin 36° t - 4.9t^2 = 0.523t - 4.9t^2 So, what is y(0.0660)?
*October 4, 2015*

**Physics**

well, the vertical position at time t is y(t) = 20 sin40° t - 4.9t^2 = 12.86t - 4.9t^2 I think that should get you started ok.
*October 4, 2015*

**Calculus**

what are we to make of L4?
*October 4, 2015*

**math221**

I'm not so sure on those examples. They are all discrete events. How about continuous versions, such as the water depth during a flood how long you are likely to sleep the temperature of fevers during family illnesses
*October 4, 2015*

**Math**

x must divide 1400, which is 2*7*2*5*2*5 Can you make a guess now?
*October 4, 2015*

**Pre-Calculus**

Assuming the "rightmost edge" of a circle is the end of the horizontal diameter, we have hole is at H:(0,0) ball is at B:(-40,-50) ball exits at P:(35,0) So, the line joining B and P is y+50 = 2/3 (x+40) The circle is represented by x^2+y^2 = 35^2 The line intersects...
*October 4, 2015*

**Math**

well, (4x10)x10 = 4x(10x10)
*October 4, 2015*

**algebra**

what's all this power stuff? 1st piece = x 2nd piece = 2x 3rd piece = 4x So, you have x+2x+4x = 28 x = 4
*October 4, 2015*

**zambia school**

you know that PV/T is constant. So, you want P where (100)(500)/(293.15) = P(22400)/(273.15)
*October 4, 2015*

**Calculus**

so, what's the trouble? You have critical numbers where f'=0. But, as you found out, f' is never zero. So, ... there are no critical numbers. There is no place where the tangent line is horizontal. Just look at the graph and sigh: http://www.wolframalpha.com/input...
*October 4, 2015*

**algebra**

since √u is defined only for u >=0, your domain here is x-2 >= 0 x >= 2 SO, the point (2,0) is the left-most point. Now plot a few more points.
*October 4, 2015*

**algebra**

can you graph the line y=4? And also y=1? If so, graph both lines, then erase the parts for the excluded domains. What's left is the graph of f. Oh, and work on your typing and prooofreading, while you're at it.
*October 4, 2015*

**math**

well, just plug in the numbers! -x+4y = -(-4/5)+4(1/3) = 4/5 + 4/3 ... I assume that since you are apparently taking algebra, you can handle the fractions, no?
*October 4, 2015*

**math**

S = dF/dr So, what's F? If you mean dU/dr, then that would be Am/r^(m+1) - Bn/r^(n+1)
*October 4, 2015*

**math**

clearly, after t hours, the population is 2^t. So, when is 2^t = 3?
*October 4, 2015*

**Algebra**

sides are 4x,x,x perimeter is 6x the desired ratio is x/6x = 1/6
*October 4, 2015*

**calculus**

ever heard of the product rule? f = 5e^x cosx f' = 5e^x cosx - 5e^x sinx = 5e^x (cosx - sinx) f" = 5e^x (cosx - sinx) + 5e^x(-sinx-cosx) = -10e^x sinx
*October 4, 2015*

** Chem**

copper sulfate reacts with sodium hydroxide producing copper hydroxide and sodium sulfate.. If sodium hydroxide is the limiting agent how many grams of copper hydroxide should precipitate out?{There are 634.44 g of copper sulfate and 240 grams of sodium hydroxide.
*October 3, 2015*

**college algebra math help**

just use the quadratic formula, as usual.
*October 3, 2015*

**Math**

right on.
*October 3, 2015*

**calculus i need help also**

assuming you meant y = 2x^3-21x^2+60x+6 y' = 6x^2-42x+60 y" = 12x-42 y"=0 when x = 7/2 For the other one, (x^1/2+x^1/3)dx = 0 ∫(x^1/2+x^1/3)dx = C 2/3 x^(3/2) + 3/4 x^(4/3) = C at x=1, C = 2/3 + 3/4 = 17/12
*October 3, 2015*

**calculus need help**

not even sure what a "differencial coefficient" is Do you mean to find the derivative, using the definition as a limit?
*October 3, 2015*

**Algebra**

using the two-point form, we have y-1 = (-3-1)/(9+3) (x+3) Now simplify and put into standard form.
*October 3, 2015*

**Chemistry**

copper sulfate reacts with sodium hydroxide producing copper hydroxide and sodium sulfate.. If sodium hydroxide is the limiting agent how many grams of copper hydroxide should precipitate out?
*October 3, 2015*

**Calculus**

C(R) = .20R C(x) = .20(70x) The notation shown is confusing, since x is used for two different things.
*October 3, 2015*

**science**

position is measured in meters. Its change in time is velocity, m/s velocity's change in time is acceleration: (m/s)/s = m/s^2
*October 3, 2015*

**science**

well, since p = mv, just do the math...
*October 3, 2015*

**Integration need help also**

To make things a bit clearer, ∫sin(x^2) x dx let u = x^2 du = 2x dx and you have ∫1/2 sin(u) du not so hard, eh?
*October 3, 2015*

**@Reiny**

That's my favorite theorem! Too bad it's not taught more. In all fairness, when you're brand new at this stuff, things often seem more confusing than they are. The main problem I encounter is that students seem to forget what the exercise set covers. If you've ...
*October 3, 2015*

**Maths**

look at the remainders when dividing powers of 2 by 13: n 2^n mod13 0 1 1 1 2 2 2 4 4 3 8 8 4 16 3 5 32 6 6 64 12 7 128 11 8 256 9 9 512 5 10 1024 10 11 2048 7 12 4096 1 ... so, you see that 2^n mod 13 = 2^(n+12) mod 13 2011 = 167*12 + 7 so, 2^2011 mod 13 = 2^7 mod 13 = 11
*October 3, 2015*

**Physics**

ever see a 5-12-13 right triangle?
*October 3, 2015*

**Maths**

If the smaller plot has width w, then w*7w = 1250/5 7w^2 = 250 w = 5.976 so, its perimeter is 2(w+7w) = 95.6
*October 2, 2015*

**Math**

(-2√2,0) Just graph the point. See that it is at the end of the diagonal of a square. Now rotate it.
*October 2, 2015*

**Geometry**

Check the related questions below. If they don't do the trick, come back with further details on why not.
*October 2, 2015*

**math**

10x = 32.222222... x = 3.2222222... subtract and you have 9x = 29 x = 29/9 Similarly, 4.(3) = 4 1/3 = 37/9 So, (29/9):(37/9) = 29:37
*October 2, 2015*

**math help**

"dash"?? Oh, please. Surely you can write y-axis! However, your answer is correct. Or, would be had you written (-5,3).
*October 2, 2015*

**science**

relative to what?
*October 2, 2015*