Sunday

December 4, 2016
Total # Posts: 46,790

**Calculus differentiable and continous identify**

For continuous, ya got me. Only F looks like it fails. For differentiable, surely F fails, because it isn't even continuous. Also, (a),(b),(d) fail because of the cusps. I am assuming that d(0) is defined somewhere on the y-axis. (f) fails because the ends of the semi-...

*October 30, 2016*

**Physics 11 steve or any physics teacher helpURGENT**

The total momentum must be conserved. If the boy slides away to the left, the box must move to the right, since momentum is a vector quantity.

*October 30, 2016*

**algebra 2**

If x is the number of years, you need (1 + .038/2)^(2x) = 3000/2000

*October 30, 2016*

**algebra**

80 is 4 half-lives, so at t=0, it was 16 (2^4) times as great.

*October 30, 2016*

**Algebra**

after x years, the value is 14000 * 0.98^x

*October 30, 2016*

**Calculus AB**

#1 f' = (3x+2)e^x since e^x is always positive, just determine where 3x+2 is positive, etc. #2 remember the point-slope form of a line. a) y= x^2 + (e^x)/(x^2 +1) at the point x=3. y' = 2x + (x-1)^2/(x+1)^2 e^x y(3) = 9+e^3/10 y'(3) = 6+e^3/4 So, you want the line ...

*October 30, 2016*

**Math**

type in your functions here, and see whether you can see how to arrive at the solutions. http://www.wolframalpha.com/input/?i=%7C(x-3)%2F2%7C

*October 30, 2016*

**math**

not sure what you have against a simple minus sign, dividion symbols, etc. The rest of us just use simple ascii characters, such as + - / * < <= > >= all are correct except #8 c+6 < -20 c < -26

*October 30, 2016*

**Pre-Calculus**

there are a few standard angles whose exact values we know. By combining them we can get exact values for other angles.

*October 30, 2016*

**Gaussian Elimination Method**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

*October 30, 2016*

**maths physics**

Let the three time periods be x,y,z seconds x+y+z = 20 (5/2 x^2) + (5xy) + (5xz-2z^2) = 20 Now, since it decelerates at 4/5 the rate that it took to accelerate, it will take 5/4 as long to come to rest. So, our third equation is z = 5/4 x Now just solve for the time periods, ...

*October 30, 2016*

**physics**

if the angle θ is measured counterclockwise from the +x axis, then the components are x = r cosθ y = r sinθ where r is the magnitude of the directed quantity.

*October 30, 2016*

**maths**

think hypotenuse.

*October 30, 2016*

**math**

see related questions below

*October 30, 2016*

**math**

I suspect a typo. Since they start with the same amount, and the first tank fills more slowly, it will never have more than the second tank.

*October 30, 2016*

**Calculus AB**

why the <note>? Just say what f(x) is. You can use the quotient rule if you want, but note that f(x) = (x-6)/(x+6) = 1 - 12/(x+6) so, f'(x) = 12/(x+6)^2 f'(6) = 12/12^2 = 1/12

*October 30, 2016*

**DISCRETE MATH**

if a_n depends on previous values of the sequence, then it is recursively defined.

*October 30, 2016*

**math- Set**

try using ⊂ for subset (a) ∅ is a subset of all sets. have any thoughts on the others? They really are quite simple.

*October 30, 2016*

**Math 107**

just plug your numbers into the formula, which I'm sure you have.

*October 30, 2016*

**maths**

x = 4/9 x + (4/9 x + 17) x = 153 girls: 68 boys: 85

*October 30, 2016*

**Math**

(10+4)(4+4) - 10*4 (19/16 + 13/4)/(13/4 - 9/16) = 71/43

*October 29, 2016*

**Calculus**

geez, why bother? It's a triangle.

*October 29, 2016*

**Calc**

you don't give an interval, but let's say it's [1,5]. If you use n rectangles, then the upper approximation will use right sums. (Draw the graph and a few rectangles to see why.) n ∑5/(1+k*4/n) k=1

*October 29, 2016*

**maths**

(115+95)km/(1.5+2.5)hr = 210/4 km/hr

*October 29, 2016*

**math**

In QIII you have x = -9 y = -1 r = √82 So, now just recall the definitions of the trig functions for a triangle in standard position.

*October 29, 2016*

**math**

clearly the first digit is 1 or 2 the cubes are 1 and 8 if 10 is a factor, the number ends in 0 start with that, and see where you get.

*October 29, 2016*

**math**

two points on the line or slope and an intercept or a point and the slope or the two intercepts ...

*October 29, 2016*

**Math**

since time = distance/speed, 6/(x-3) = 6/x + 1

*October 29, 2016*

**physics**

PV = kT, so PV/T is constant. So, you want P such that (P)(120)/(40+273) = (1)(140)/(20+273)

*October 29, 2016*

**Math**

use the law of cosines. The angle between the bearings is 35+32 = 67 degrees.

*October 29, 2016*

**math**

6*(2(15+31)-5)

*October 29, 2016*

**Calculus**

Use as many as you want. That's the n. You can estimate the area with a single rectangle, of width pi/2 and height 1, but it won't be a very good estimate. Also, my bad. I was thinking of sin(x) when I mentioned that the estimate was over- or under-. The reverse for ...

*October 29, 2016*

**Calculus**

n ∑(pi/2n)(cos(t*pi/2n) t=1

*October 29, 2016*

**Calculus**

It's a good start. Note that since you are using the right-side sum, and cos(x) is concave down and rising on that interval, the sum will be an upper estimate. Use the left-side sum for a lower estimate. Draw a few rectangles and the curve to see why this is true.

*October 29, 2016*

**Math**

use the law of cosines.

*October 29, 2016*

**1 MATH QUESTION**

the number off coordinates.

*October 29, 2016*

**Math**

see related questions below

*October 29, 2016*

**Trigonometry**

The angle of depression from the top of a lighthouse across the street is 65 degrees. the angle from the lighthouse to what? And across the street from what? All we know is that the lighthouse is 37 tan28° = 19.67 ft taller than the house.

*October 29, 2016*

**Chemistry**

well, velocity = wavelength * frequency

*October 29, 2016*

**Math**

well, 1000 years is 2 half-lives, so ...

*October 29, 2016*

**Algebra 2**

Assuming that sqrt4(125) means ∜125, then A = 3^(1/2) * 5^(3/4) / 7^3 so, logA = (1/2)log3 + (3/4)log5 - 3log7 The base of the logs does not matter. The rules still hold.

*October 29, 2016*

**math**

Recall that for x^2+bx+c the product of the roots is c. If the other root is m, then 4m = k 4+m = 5 Looks like m=1, so k=4 x^2-5x+4 = (x-4)(x-1)

*October 29, 2016*

**Math**

just multiply all the numbers by 2.

*October 29, 2016*

**maths**

start with 1 and 24 Now start increasing the first and decreasing the second till they ass each other. By then you will have listted all the factors.

*October 29, 2016*

**Math**

consider that the amount of sausage never changed. did the solvent remove the fat?

*October 29, 2016*

**Math's**

well, how many oranges in 2 dozen?

*October 29, 2016*

**math**

1.7/B + 1/B = 1/6

*October 29, 2016*

**Maths**

multiply the rows by 3 and 2 and you have 6x-9y = -9 6x-14y = -2 Now subtract to eliminate x, and then y is easy. Use that value of y in either equation to get x.

*October 29, 2016*

**math**

must be all 9's, eh?

*October 29, 2016*

**Math probability**

well, what is the chance that the 1st sock is blue? Having removed it, what is the chance that the 2nd is blue? The number of blues and the number of socks have both been changed by removing the 1st blue sock. Now just multiply.

*October 29, 2016*

**math**

a = F/m, so plug in your numbers.

*October 29, 2016*

**Math Help**

It means the number of elements in the set. Clearly you have not studied your material.

*October 29, 2016*

**Math Help**

so, do you know what n(a) means? If you do, this cannot be a hard problem.

*October 29, 2016*

**math**

ha ha if you can read, just put it into math. If the river's speed is x, then since time = distance/speed, 4/(2+x) = 1/(2-x)

*October 29, 2016*

**math**

google is your friend https://www.quora.com/How-do-you-calculate-the-number-of-squares-in-an-n-x-n-square-grid

*October 28, 2016*

**maybe math**

If Reiny is right, then to simplify, -1/8 + 1/8^2 = -8/8^2 + 1/8^2 = -7/8^2 or, 2 ∑ -2^k/8^2 k=0 How's that for simple? And all positive exponents!

*October 28, 2016*

**Math Derivative**

yes. The good old chain rule. It helps to write them as fractions, so things cancel out: dg/dx = dg/dh * dh/dx I know they usually tell you to avoid thinking of derivatives as fractions, but they really are. It's the same with parametric functions, x(t) and y(t) dy/dx = (...

*October 28, 2016*

**Calculus**

a scalar multiple just distributes as in a complex number: a(x+yi) = ax+ayi (1/2)<-3,7> = <(1/2)(-3),(1/2)(7)>

*October 28, 2016*

**Physics**

conserve total angular momentum.

*October 28, 2016*

**Calculus**

well, y' = -2/(3y), so y" = 2/(3y^2) y' = ...

*October 28, 2016*

**Calculus I**

show what you did. This kind of problem always works out that the fencing is divided equally among lengths and widths. So, the entire array will have dimension (50/3) by (50/4) Each pen will be (50/9) by (50/8) Start with 3x+4y = 100 a = xy = x*(100-3x)/4 then find x such that...

*October 28, 2016*

**Math (Confused)**

9*10^3 * 9*10^4

*October 28, 2016*

**Math (Finding Vertical Tangent)**

looks to me like there is a vertical tangent at x = 2pi/3

*October 28, 2016*

**Algebra**

75% is correct. There is a mistake somewhere in the problem or the answer. Could it be that they won 6 and lost 8? That would make the answer 6/14 instead of 6/8.

*October 28, 2016*

**Chem**

1 mole occupies 22.4L at STP so, you will have 17.8*22.4L PV = nRT

*October 28, 2016*

**Algebra**

cost = revenue to break even So, what is the cost for x pencils?

*October 28, 2016*

**Math**

need for what? and how much is a "dash"?

*October 28, 2016*

**Math**

if x mL were lost and replaced, then .80(250-x) + .40x = .72*250

*October 28, 2016*

**Math - forget it**

Oops - my bad. I misread it. Embershy is correct

*October 28, 2016*

**Math**

23/40 - 23/30 = 23(1/40 - 1/30) = 23(3/120 - 4/120) = 23(-1/120) = -23/120 Note above that 23/30 is not 11/15.

*October 28, 2016*

**Math**

.30*8 + 1.00x = .35(8+x)

*October 28, 2016*

**Chemistry**

The total mass of the solution is x where .0910x = 19.0

*October 28, 2016*

**maths**

660 is nowhere close. You want the circumference of a circle. You don't say whether 220 ft is the diameter or the radius, or even the circumference. If the diameter, your new larger circle has diameter 220+6 = 226 If the radius, your new larger circles has diameter 440+6...

*October 28, 2016*

**easy Math**

well width * length = area so, ...

*October 28, 2016*

**easy math**

(6/2)^2

*October 28, 2016*

**algebra**

6.50 per hour means the hourly charge will be 6.50h so, now what do you think?

*October 28, 2016*

**Calculus**

cosh(3x) = cosh(2x+x) = cosh2x coshx + sinh2x sinhx ...

*October 28, 2016*

**BASIC TECH**

How about some English? With the aid of compass and ruler bisect a line of 12 cm. The length of the line does not matter for the construction. Draw the line AB. Open the compass to more than half the length of AB. From A, draw an arc From B, draw an arc The two arcs (if long ...

*October 28, 2016*

**Maths**

x^2-36 and 2x^2-15x+18 so what?

*October 28, 2016*

**MATHS URGENT**

9/u + 4u = -12

*October 28, 2016*

**MATHS URGENT**

ok ok never mind looking at the related questions. 7^(2x-1) = 7^(2x)/7 4*7^(x-1) = 4*7^x/7 so, doing what they suggested, you have u^2/7 + 4u/7 - 1/14 = 0 Think you can handle that?

*October 28, 2016*

**Physics**

v = at and acceleration is m/s^2, not m/s

*October 28, 2016*

**math**

3C-243

*October 28, 2016*

**Math**

since time = distance/speed, 10/(v+5) = 8/(v-5)

*October 28, 2016*

**9th grade algebra (factoring)**

all correct. Good job.

*October 27, 2016*

**math check answers**

how did you arrive at that amount? The monthly interest rate is only .035/12

*October 27, 2016*

**Math**

Add up the total of all the ages. You have for x people, 41(x-2) + 86+84 = 45x

*October 27, 2016*

**math**

x: v*cos(theta) y: v*sin(theta)

*October 27, 2016*

**Physics**

see the related questions below. Think of polar coordinates, and place the starting point at (r,0)

*October 27, 2016*

**Math**

768 = 3*2^8

*October 27, 2016*

**Math**

well, there's no equation, but the derivative of that expression is just 6(x^2+y^2)^5 * (2x + 2yy')

*October 27, 2016*

**Math**

Implicit Differentiation for (x^2+y^2)^6

*October 27, 2016*

**calculus**

see your previous post - in the related questions below

*October 27, 2016*

**math**

x(1 - 1/4 - (3/4)(3/5)) = 3600

*October 27, 2016*

**Math**

Hydrogen

*October 27, 2016*

**Math (Derivative)**

The definition is the limit of f(x+h) - f(x) ----------------- h That is where the subtraction comes in.

*October 27, 2016*

**Math (Derivative)**

uh -- from the definition of the derivative. Better reread it.

*October 27, 2016*

**math**

Oops - my bad. I was looking for volumes. The overlap is the area of the circular base of the cone (pi r^2) and the circular base of the hemisphere (pi r^2). Subtract it twice, once for each solid.

*October 27, 2016*

**math**

surely you have the formulas for finding the volumes of these solids. Just add 'em up. What do you get? Show work if you get stuck.

*October 27, 2016*

**Economics**

If you borrow $1000 from the bank, and the effective annual rate is 9.4% with monthly compounding. How much do you pay after 2 years?

*October 27, 2016*