Wednesday

January 28, 2015

January 28, 2015

Total # Posts: 28,440

**ap calc**

f(0) = 0 f(√π) = 0 So, we need c in (0,π) such that f'(c) = 0 f'(x) = 2x cos(x^2) 2x cos(x^2) = 0 Clearly c=√(π/2) satisfies the theorem.
*December 19, 2014*

**Math**

just divide each y by its x. Is the ratio constant? If so, that means y/x = k,or y=kx, a direct variation.
*December 19, 2014*

**math**

We have a winner!
*December 19, 2014*

**Math**

Note that y increases 5 when x increases 1. So, the rule will look like y = 5x But, when x=0, 5x=0 and we want y = -3. So, y = 5x-3
*December 19, 2014*

**Intermedia Algebra**

well, you have the formula. Use it. What do you get?
*December 19, 2014*

**Algebra**

Neil: 2 mi/hr current: 1 mi/hr Check: In 1 hour, Neil rowed 1 mi upstream. In 1 more hour, he rowed 3 mi downstream back to camp In those 2 hours, the log floated 2 miles downstream to camp
*December 19, 2014*

**math**

Hmph. Musta missed that. Using 22/7 for pi is just not rational!
*December 19, 2014*

**math**

so, what does 22/7/2 mean?
*December 19, 2014*

**math**

A makes 3x B makes 4x A spends 4y B spends 5y So, A saves 3x-4y B saves 4x-5y So, can you solve (3x-4y)/(4x-5y) = 9/10 ? 10(3x-4y) = 9(4x-5y) 30x-40y = 36x-45y 6x = 5y Can't happen try the other fractions.
*December 19, 2014*

**Math**

dy = 1/3 x^-2/3 dx At x=4, dy = 1/48 dx So, use dx=0.2 to find dy, and add that to y(64)=4 Note also that since the slope is 1/48, y-4 = 1/48 (x-64)
*December 19, 2014*

**Math**

this is just algebra I, after finding the slope of the tangent line... since y = x^(1/3) y' = 1/3 x^-(2/3) y(27) = 3 y'(27) = 1/9 So, now you have a point and a slope, so the line is y-3 = 1/9 (x-27) I'll let you massage the equation. Now you can use that line to ...
*December 19, 2014*

**Math**

since v = 4/3 pi r^3 and c = 2pi r, r = c/2pi, and v = 4/3 pi (c/2pi)^3 v = 1/(6pi^2) c^3 so, dv = 1/(2pi^2) c^2 dc so, now you have dc and can evaluate dv
*December 19, 2014*

**math**

Post a problem, showing your work as far as you got. Hope someone who knows something drops by to help out.
*December 19, 2014*

**precalculus**

[-7,-4)U(-4,-1)
*December 19, 2014*

**precalculus**

revenue r(x) = (1000+4x)(500-8x) Just find the vertex of that parabola to get the x desired, then figure the other items based on that.
*December 19, 2014*

**Algebra**

ever hear of the slope-intercept form of the line? Just plug in the numbers given.
*December 19, 2014*

**math**

A makes 4x B makes 3x A saves 3x/4 So, A spends 4x - 3x/4 = 13x/4 B spends (4/5)(13x/4) = 13x/5 So, B saves 3x - 13x/5 = 2x/5 The savings ratio is thus (3x/4):(2x/5) = 15:8
*December 19, 2014*

**algebra**

I think you need to (a) indicate how far apart are the integers (b) just what it is you want to know.
*December 18, 2014*

**math**

Hard to say: out = in-16 ? out = in/3 ? out = 2 * in(mod 5) ? One data point does not give much to go on.
*December 18, 2014*

**Algebra 1**

depends on the equations. Mainly, as with most things, skill comes with practice. Just doing the 5 assigned homework problems isn't going to give you the practice you need. I'm good at it because I have done hundreds of them.
*December 18, 2014*

**Algebra 1**

When solving a system of equations, how do you determine which method to use?
*December 18, 2014*

**Algebra math**

have you considered taking a typing class? You want to find when the height h: 80t - 16t^2 = 0 16t(5-t) = 0 I think it's clear now when h=0. (Just in case you haven't figured it out, the ball hits the ground when the height is zero...)
*December 18, 2014*

**Algebra 1**

thank you
*December 18, 2014*

**Algebra 1**

Which method would be the simplest way to solve the system? 7x +5y = 19 -7x-2y = -16 graphing substitution elimination or distributive
*December 18, 2014*

**Algebra 1**

I forgot my answer which is quadrant III.
*December 18, 2014*

**Algebra 1**

In which quadrant does the solution ofthen system fall? y=x-1 y= -3x-5
*December 18, 2014*

**Algebra 1**

$7.00 Thank you
*December 18, 2014*

**Algebra 1**

The cost of 4 scarves and 6 hats is $52.00. The cost of 2 hats is $1.00 more than the cost of 1 scarf. What is the cost of 1 scarf?
*December 18, 2014*

**Algebra 1**

Thank you
*December 18, 2014*

**Algebra 1**

zero solutions. -3x+6y cannot equal both 10 and -4. The lines are parallel, and so, do not intersect.
*December 18, 2014*

**Algebra 1**

The first line should read -3x
*December 18, 2014*

**Algebra 1**

How many solutions does this system have? *3x + 6y = 10 -3x + 6y = -4
*December 18, 2014*

**algebra 1**

that is correct. If you dislike working with fractions, you can start over and eliminate y instead of x.
*December 18, 2014*

**algebra 1**

-16x-2y=-18 8x+y=9 Multiply the 2nd by 2 to get -16x-2y=-18 16x+2y = 18 These are the same line. There are infinitely many solutions. Any point on one line is also on the other, as the lines coincide.
*December 18, 2014*

**physics**

when you say constant velocity, that means zero acceleration.
*December 18, 2014*

**Chemistry**

(.0658*0.3)/(.015)
*December 18, 2014*

**Math**

count the deposits, and count the amounts: If there were x deposits at $5, and y at $3.50, then we know x+y=14 5x+3.50y=59.50 Now just plug and chug.
*December 18, 2014*

**Chemistry**

Since PV is constant, and you have increased the volume by a factor of 1000, the pressure is reduced by a factor of 1000.
*December 18, 2014*

**math**

Since the 54% and the 63% grades count as 80% of her grade (and assuming therefore that each counts as 40%), the final grade is (54+63)(0.4) + 80(.2) = 62.8
*December 18, 2014*

**math**

If they sell x tacos, the profit for the day is 3.25x - 210 So, set that > 0 and solve for x.
*December 18, 2014*

**Math**

correckit!
*December 18, 2014*

**Math**

if it is not included, then you subtract it from the total. So, ...
*December 18, 2014*

**math algebra**

Since y is the cost of a sandwich with x extra veggies, the y-intercept is the cost with 0 veggies. the two extra veggies (5-3) cost $1.00 more. So, the veggies are $0.50 each. That means 0 extra veggies (the y-intercept) must be at 5.25-1.50 = 3.75 Looks like (D) to me y = 0....
*December 18, 2014*

**physic**

well, torque = radius * force T = rF if the radius is doubled, the new torque is T' = (2r)F = 2rF = 2T
*December 18, 2014*

**Physics**

If he cleared the bar at the top of his swing, then all his speed was horizontal, at 10.2 m/s. All that stuff about mass and height is just noise. Trying to incorporate other forces is impossible without further data.
*December 18, 2014*

**Physics**

speed s is found by conserving momentum: 800s = 3*10 time = 6.4/s
*December 18, 2014*

**math**

d/dr (r^3) = 3r^2 It's just the normal power formula So, dV/dr = (4/3)pi (3r^2) dV = 4pi r^2 dr Don't lose track of the dr when doing related rates
*December 18, 2014*

**Math**

well, dy = -1 / 2√(7-x) dx So, just plug in your numbers
*December 18, 2014*

**algebra**

you need an equation for the number of plays and the points for them: x+y = 21 3x+y = 49
*December 18, 2014*

**math**

The price p for e eggs is p/e = 1/6
*December 18, 2014*

**Math**

well, just compare the two plans for how much it costs the patient: 400 + 0.35(x-400) > 1000 + 0.25(x-1000)
*December 18, 2014*

**math**

.85p = 76
*December 18, 2014*

**Math- algebra**

well, you want y when x = -b/2a = 26/32 google will evaluate many algebraic expressions. Just type it into the search box.
*December 17, 2014*

**math**

15/x = cos 60°
*December 17, 2014*

**math**

clearly, 23.25/3 or 7.75
*December 17, 2014*

**math**

well write the ratios and see which are the same when reduced to lowest terms. For example 6/3 and 20/10 are the same ratio
*December 17, 2014*

**Algebra 1**

Describe how the graphs of y = absolute x and y = absolute x +2 are related.
*December 17, 2014*

**Calculus**

since f'(x) = -1 which is never zero, there are no relative min or max points. So, the extrema will just be the values at the endpoints of the interval. So, just find f(-1) and f(2). I mean, don't forget your Algebra I just 'cause you're in calculus now. f(x) ...
*December 17, 2014*

**math**

25q+5n+10d = 4500 q = 5n n = 3d So, start substituting and the values will become clear.
*December 17, 2014*

**AP AB Calculus**

(c),(d) just plug in 4.2 for x and solve for y. That will be the value for k. Since (d) will be a cubic in y, it might take a graphical solution.
*December 17, 2014*

**Algebra 1**

Write the equation of a line that is perpendicular to the given line and that passes through the given point. y-3 = 8/3 (x+2); (-2,3)
*December 17, 2014*

**Math**

u^-3 = 1/125 u^-3 = 5^-3 u = 5 y-1 = 4y - 2/3 3y-3 = 12y-2 9y = -1 y = -1/9 The y-intercept is where x=0. Clearly when x=0, y = -5, not 5. If she ran x miles, then we know that x+40 = 10+4x x = 10 If you want the slope, try writing the equation is slope-intercept form: 4x-6y+...
*December 17, 2014*

**Algebra**

I'd do C
*December 17, 2014*

**Algebra 1**

just change the slope to -1/(8/3)
*December 17, 2014*

**Algebra 1**

Write the equation of a line that is perpendicular to the given line and that passes through the given point. y-3 = 8/3(x+2); (-2,3)
*December 17, 2014*

**Math! 2 question! Need help!**

why not just review your point-slope form? The line passing through (h,k) with slope m is y-k = m(x-h) Now just plug in your values.
*December 17, 2014*

**calculus honor**

hey, honor student -- find what when x=1?
*December 17, 2014*

**calculus**

v = pi r^2 h dv/dt = pi r^2 dh/dt
*December 17, 2014*

**calculus**

a = pi r^2 da/dr = 2pi r
*December 17, 2014*

**Math( Can you help me with starting this problem)**

hmm. They gave you the formula, so just use it: v = 4/3 pi r^3 dv/dt = 4pi r^2 dr/dt So, just solve for dr/dt
*December 17, 2014*

**caculus**

If the base of the ladder is x from the wall, and the top of the ladder is y high, then x^2+y^2 = 10^2 x dx/dt + y dy/dt = 0 So, figure y when x=6 and just plug in the numbers to find dy/dt.
*December 17, 2014*

**Algebra**

so, plug in the numbers. solve for t when h=84 and 0
*December 17, 2014*

**math**

(2.6)(2.2)x10^(-4+8) = 5.72 x 10^4
*December 17, 2014*

**Algebra 1**

Tell whether them lines, for each pair of equations are parallel, perpendicular, or neither. y= -1/4x +10 -2x+8y=6
*December 17, 2014*

**math**

the three sizes clearly have different constants. For n dozen eggs, For the one-dozen size, p = 2(6.00n) For the half-dozen size, p = 2.18n For the 1 1/2-dozen size, p = (2/3)(3.00n)
*December 17, 2014*

**Algebra 1**

thank you
*December 17, 2014*

**Algebra 1**

Tell whether the lines for each pair of equations mare parallel, perpendicular, or neither. y= -2x+4 -5x+10y=5
*December 17, 2014*

**math**

My answers: 1. B 2. C 3. C 4. A
*December 17, 2014*

**Algebra 1**

Write an equation for the line that is parallel to the given line that passes through the given point. y=3x+7; (2,10)
*December 17, 2014*

**math**

I assume you mean leveling the ground for the roads. 3(225*5 + 175*5) = ? This assumes that the intersection is leveled twice.
*December 17, 2014*

**Algebra**

just factor y to get y = x(85-16x) So, what is x when y=0 (that is, when it hits the ground)?
*December 17, 2014*

**Algebra II**

If there are x price decreases, then price = 6.00 - .25x or 6-x/4 demand = 330 + 15x Since revenue = price * quantity, r(x) = (6-x/4)(330+15x) = -15/4 x^2 + 15/2 x + 1980 Now use what you know about parabolas to find the vertex. Since this parabola opens downward, the vertex ...
*December 17, 2014*

**Math**

If side x is parallel to the river, xy=1800 The perimeter is p = 2(x+y) = 2(x + 1800/x) p is a max when 1 - 1800/x^2 = 0, or x = 30√2 So, the field is 30√2 by 30√2 As usual, maximum area (or minimum perimeter) is achieved by a square.
*December 17, 2014*

**Maths**

h = 2g 2h+4g+h+g = 99 So, 11g = 99 g=9 9 goats and 18 hens
*December 17, 2014*

**Mathematics**

the first thing I'd do is divide by 20E6 and get 2/x - 3/(.5-x) = 0 2/x = 3/(.5-x) 2(.5-x) = 3x 1 - 2x = 3x x = .2
*December 17, 2014*

**Math**

amplitude = (8-5)/2 period = (5π-3π)*2 = 4π Assuming the cited min and max are consecutive extrema (that is, half the cycle)
*December 16, 2014*

**Algebra**

(3x+4)^5 = 4^15 = (4^3)^5 So, 3x+4 = 4^3 = 64 x = 20 That's the only solution I see.
*December 16, 2014*

**Algebra 1**

Write y= -2/3x +7 in standard form using integers.
*December 16, 2014*

**Calculus**

Hmmm. As I recall, the average value of f(x) on [a,b] is ∫[a,b] f(x) dx ------------------ b-a e^(4x^2) is an even function, so its average value cannot be zero over [-1/4,1/4]. ∫[-1/4,1/4] e^(4x^2) dx Unfortunately, ∫e^(x^2) dx is not an elementary integral.
*December 16, 2014*

**Algebra 1**

thank you
*December 16, 2014*

**Algebra 1**

Write an equation in point slope form for the line through the given point with the given slope. (4,-7); m= -0.54
*December 16, 2014*

**calculus**

no, s(t) is the position function. You want the velocity, which is ds/dt = -9.8t then you can sub in t=3. And, since the ball is falling, s(t) = -4.9t^2 + 550
*December 16, 2014*

**Trig/Precalc**

Yes, there are lots of such formulas. One is at http://www.uwfox.uwc.edu/users/tnyman/TRIGConcepts/Asinx+Bcosx.pdf where you will see that the amplitude of your function is √(5^2+6^2) = √61
*December 16, 2014*

**Algebra 2**

ax+by=c ax=c-by x = (c-by)/a
*December 16, 2014*

**math**

Mr jacob is 55 years old and Tony is 7 years old. In how many years will Mr. Jacob be 4 times as old as Tony?
*December 16, 2014*

**math**

The cost of 5 similar digital cameras and 3 similar video cameras is $3213. each video camera costs 4 times as much as each digital camera. John buys a digital camera and a video camera. How much does he pay?
*December 16, 2014*

**math**

Three times as many children as adults attended a concert on Saturday. An adult's ticket cost $7 and child's ticket cost $3. the theater collected a total of $6,000. How many people bought tickets?
*December 16, 2014*

**English - Writeteacher**

Your choices look good to me.
*December 16, 2014*

**math**

(4/56)*42 Or, you can write that as x/42 = 4/56
*December 16, 2014*

**Chemistry**

I think that the crystal lattice has little to do with it at this point. By saying that the Al atom has a volume, they just want you to divide the mass of an atom by its volume. Without more information on the lattice spacings in 3D, it's hard to say how much space an atom...
*December 16, 2014*

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