Monday

December 22, 2014

December 22, 2014

Total # Posts: 27,667

**science **

A running back has 3500 J of kinetic energy and is running at a speed of 8 m/s. Calculate his mass.
*December 21, 2014*

**Integration**

The trapezoidal cross-section for water at depth 1/2 + h/2 = (1+h)/2 So, the surface area of the water at depth h is 10*(1+h)/2 = 5(1+h) So, the volume of the sheet of water is 5(1+h) dh That means that the weight of the water (at 1000kg/m^3) layer is 5(1+h) dh * 1000 * 9.8 ...
*December 21, 2014*

**ap calc**

Is f(x) continuous at x=1? 2x-x^2 = 1 2x^2-4x+3 = 1 So, yes. The derivative exists everywhere in (0,2). So, f(x) satisfies the MVT f(2) = 3 f(0) = 0 So, the slope of the secant is is 3/2 Where does f'(c) = 3/2? 2-2x = 3/2 x = 1/4 y = 3/2 (x-1/4) + 7/16 4x-4 = 3/2 x = 11/8 ...
*December 21, 2014*

**Algebra**

Just plug the numbers into your amortization formula.
*December 21, 2014*

**College Math**

find the mean and the standard deviation. The Z score of 3.1 is how many std it is away from the mean.
*December 21, 2014*

**College Math**

zero The Z score of the mean is always zero, because it is zero std away from the mean. If you really have no clue, it's probably time to review just what a Z score is.
*December 21, 2014*

**College Math**

30(1.6)^n = 30000 1.6^n = 1000 n log 1.6 = log 1000 n = log1000/log1.6 = 14.7
*December 21, 2014*

**Algebra 1**

just plug in the numvers and check. 4 > 4*3-5 ? 4 > 12-5 ? 4 > 7 ? NO So, try the others.
*December 21, 2014*

**Algebra 1**

Which ordered pair is a solution of the inequality? y>= 4x-5 3,4 2,1 3,0 1,1
*December 21, 2014*

**math**

what a deal. I suspect you want to start with what you know: 4s+3j = 181 1s+2j = 94
*December 21, 2014*

**ap calc**

y = x ln x + (1-x) ln(1-x) y' = lnx + 1 - (1-x)/(1-x) - ln(1-x) = lnx - ln(1-x) = ln(x/(1-x)) y'=0 when x/(1-x) = 1 x = 1-x x = 1/2
*December 21, 2014*

**Math-How do I do this problem?**

Hmmm. I get r = 7/24 h so, dr = 7/24 dh r = 35/12 when h=10 v = 1/3 pi r^2 h using the product rule, dv = 1/3 pi (2rh dr + r^2 dh) 12 = pi/3 (2*(35/12)(10)(7/24 dh)+(35/12)^2 dh) 12 = 1225/144 pi dh dh = 1728/1225 pi = 12^3/35^2 pi Maybe you can figure out whether one of us is...
*December 21, 2014*

**Calculus**

The curves intersect at (-4,-12) and (3,-5) So, the area is just the sum of all the tiny rectangles with width dx, and height the distance between the curves: A = ∫[-4,3] (4-x^2)-(x-8) dx = ∫[-4,3] -x^2-x+12 dx = -1/3 x^3 - 1/2 x^2 + 12x [-4,3] = 343/6
*December 21, 2014*

**Calculus**

Try checking here: https://in.answers.yahoo.com/question/index?qid=20101212020426AAEM8Zp and https://answers.yahoo.com/question/index?qid=20131119231723AABFnM7
*December 21, 2014*

**Algebra 1**

What about from the following answers 0,1 -1,0 1,0 0,0 I'm a 68 year old grandfather trying to help his grandson.
*December 20, 2014*

**Algebra 1**

the solution set for y<x is half of the plane. There are infinitely many points on each axis which satisfy the inequality.
*December 20, 2014*

**Algebra 1**

Which point on the axis satisfies the inequality y<x?
*December 20, 2014*

**Algebra 1**

What about from the followuing answers 4 -2 2 -4
*December 20, 2014*

**Algebra 1**

the point on the x-axis is where y=0, SO x - 2y <= 4 now plug in y=0 and you can see what x is. I think you need a bit more information here.
*December 20, 2014*

**Algebra 1**

In the graph of the inequality X - 2y is less then or equal,to 4, which is a value for x on the inequality line and the x axis?
*December 20, 2014*

**Algebra 1**

I'm 68 years old and don't remember some of these things and am trying to help grandson.
*December 20, 2014*

**Algebra 1**

draw the axes. Label each quadrant ++ +- -+ or -- and then let us know, ok?
*December 20, 2014*

**Algebra 1**

If x is greater then or equal and y is greater then or equal to 0 then which quadrant holds the solution?
*December 20, 2014*

**Algebra 1**

the rate of change is the slope of the line. That is, if x changes by 1, how much does y change? In the slope-intercept form, the rate of change (slope) is m, in y = mx+b The point-slope form of a line is y-k = m(x-h) where the line passes through (h,k) with slope m. It's ...
*December 20, 2014*

**physics**

well, you know the equation of motion is h(t) = vt - 4.9t^2 So, h is max at t = v/9.8 So, plug in t=v/9.8 into vt - 4.9t^2 = 1.5 and solve for v.
*December 20, 2014*

**physics please help**

If thrown down with initial velocity v, then just solve 109 - vt - 4.9t^2 = 0 plug in t=2.40 and find v.
*December 20, 2014*

**Physics please help**

the equation of the height is h(t) = 29t - 4.9t^2 Now just find the vertex of the parabola for the max height. Of course, the ball comes down exactly as fast as it went up -- got to conserve that momentum, eh?
*December 20, 2014*

**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*

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