Sunday
January 25, 2015

Posts by STEVE


Total # Posts: 28,309

physics
three light sources at different directions, maybe of different sizes.
December 26, 2014

statistic
exactly half. It doesn't matter what the std is. In a normal distribution, 1/2 of the population is above or below the mean.
December 26, 2014

Math
There are only 3 colors. So, after 6 draws, it is possible to have two of each color. The 7th ball must be the one which matches two of the others.
December 26, 2014

math
3+4+5+6+7 = 25 So, the milk in the vessels is 3x,4x,5x,6x,7x If the capacity of each is z, then 25x = 0.6*5z = 3z x = 0.12z So, in terms of a full vessel, the amounts of milk in each of the vessels is .36, .48, .60, .72, .84 Looks like 3 of them are over 50% full.
December 26, 2014

Math
hint: the equation you have shown is called the slope-intercept form of a line. Just read off the slope and the y-intercept...
December 26, 2014

Business Math
have you no calculator? Heck, just type it into google, if nothing else.
December 26, 2014

science
the circumference is C = 2pi*r. Make sure your answer is in meters, not cm. Opposite ends of the diameter are half that far apart. Now just multiply that by 12.
December 26, 2014

maths
you surely have the formula for the surface area of a sphere. Divide that by 4.
December 26, 2014

s.p s
TODAY (actually, since it's not yet midnight here where I am, there's no way!)
December 26, 2014

Algebra
F(x) = -3cos(4(x+n/4))+6 So, the amplitude is 3 the period is 2pi/4 = pi/2 the phase shift is -n/4
December 25, 2014

Math
the period and amplitude do not change, whatever the value of t. The question asks for three things: amplitude frequency distance when t=3 The distance when t=3 is y(3) = -15cos((pi*3)/3)+5 = -15cos(pi)+5 = 15+5 = 20
December 25, 2014

Math
(a) The period is (2pi) / (pi/3) = 6 so, the frequency is 1/6 your amplitude and distance are correct. Remember, the period for cos(kt) is 2pi/k So, (b) should be no trouble now.
December 25, 2014

math
Your answers are correct.
December 25, 2014

algebra
(x-2)(3(x+6)-5(x-3)) (x-2)(3x+18-5x+15) (x-2)(-2x+33) -2x^2+37x-66 or 3(x^2+4x-12)-5(x^2-5x+6) 3x^2+12x-36 -5x^2+25x-30 -2x^2+37x-66
December 25, 2014

precalc
Suppose the closer point is at distance x. Then you have h/x = tan 20° h/(x+25) = tan 12° eliminate x and you have h/tan20° = h/tan12° - 25 h = 25/(cot12°-cot25°) = 12.774
December 25, 2014

maths
What atrocious spelling (even for texting!) and grammar. I assume by "my number" you mean "my numerator." If so, then 21/3 = 7
December 25, 2014

Math (PreCalculus)
If you have no ideas on any of these questions, you seriously need to review your trig functions. y = 5+3sin(πt-π/2) = 5+3sin(π(t-1/2)) (a) at t=0, y = 3sin(-π/2) = -3 Since that is below the equilibrium point, the weight was pulled down. (b) all these ...
December 25, 2014

Math (PreCalculus)
A spring with a weight attached is oscillating. The weight (which is attached at the bottom of the spring) is 5 feet from a 10-foot ceiling when it’s at rest. The motion of the weight can be described by the equation: y=3sin(pi*t - pi/2) , where y is the distance from the...
December 25, 2014

maths
By "equal" I assume you mean with the same surface area. So, naturally, each part has 1/4 of the total original surface area.
December 25, 2014

university bahrain
Probably true. And ? ...
December 25, 2014

binomial
(x+8y)^5 = x^5 + 5x^4(8y) + 10x^3(8y)^2 + ... = x^5 + 50x^4y + 640x^3y^2 + ... Now just plug in x=1 and y=.01
December 25, 2014

Math (PreCalculus)
The tip of the second hand travels on a 4" circle, inside a 5" circle. So, at t seconds into the minute, the tip of the second hand is at height 5+4cos(t/60 * 360)° = 5 + 4cos(6t)° from the bottom of the clock.
December 24, 2014

Algebra 1
if x gallons are 12%, then the rest (20-x) are 7%. So, adding up all the amounts of sugar, you need to solve .12x + .07(20-x) = .10(20) x = 12 You may have worked the problem correctly, but you got your answers switched. Note also that equal amounts of the two would have ...
December 24, 2014

Algebra 1
A restaurant has one type of lemonade that is 12% sugar and another that is 7% sugar. How many gallons of each type does the restaurant need to make 20 gallons of a lemonade mixture that is 10% sugar? I think the answer is 8 gallons of 12% lemonade and 12 gallons of 7% lemonade
December 24, 2014

Algebra 1
thank you
December 24, 2014

Algebra 1
A local citizen wants to fence a rectangular community garden. The length of the garden should be at least 110 ft and the distance around should be no more than 380 ft. What system of inequalities would represent the possible dimensions of the garden?
December 24, 2014

Good One, Damon
Oh, yeah. I like it. I think I pooh-poohed that derivation on another problem, thinking you had short-circuited the product rule, but this time I studied it more closely. Of course dv is just a thin circle on top of the cone (pi r^2) times the thickness (dh)!
December 24, 2014

Calculus
Or, you can use the product rule: v = 1/3 pi r^2 h dv/dt = 1/3 pi (2rh dr/dt + r^2 dh/dt) Then you have to fill in the other quantities to get dh/dt. Note that since r = h/2, dr/dt = 1/2 dh/dt
December 24, 2014

Calculus
Once you master the math, you can work on the spelling!... we know h = 2r, so r = h/2 v = 1/3 pi r^2 h = 1/12 pi h^3 dv/dt = 1/4 pi h^2 dh/dt So, now just plug in the numbers you have for h and dv/dt to find dh/dt.
December 24, 2014

Math
which bank is that? I'll put my money there!
December 24, 2014

math
A:B:C = 3:7:8 A:B+10:C-10 = 3:8:7 That means that b/c = 7/8 (b+10)/(c-10) = 8/7 Solving that, we have b=70 c=80 Now, you can figure a.
December 24, 2014

Algebra 1
How many solutions does then system of equation have? y-5x = -6 and 3y-15x=-12
December 23, 2014

Algebra 1
How many solutions does the system of equation have? x-4y =12 and 5x-20y =60
December 23, 2014

Math I Have no idea PlEASE help me
well, you know that flying east-to-west, the plane goes 270 mi/hr going to the east, it flies at 330 mi/hr. So, just make your table for each 200-mile interval. That's 15 entries in each direction.
December 23, 2014

Algebra 1
How many solutions does the system of equations have? y=4x +3 and 2y-8x=3
December 23, 2014

Algebra 1
How many solutions does the system of equations have? x=-4y+4 and 2x+8y=8
December 23, 2014

Geometry
It might help if you list the vertices of the quadrilateral, say, in clockwise order or something. What you have said gives no real good picture of the figure.
December 23, 2014

math
Ah, yes. You are correct. I had misread the problem. Good work.
December 23, 2014

math
Clearly, the fixed charge is always 700. You must want the variable charge per unit. That means you want to solve 700+200x = 5/4(700+100x) unless something else has been garbled.
December 23, 2014

Maths
6912/(3+4) = 987.4 So, length = 3*987.4 breadth = 4*987.4
December 23, 2014

Algebra
just write down what you know. If there are x at 5 points and y at 3 points, then x+y = 38 5x+2y = 100
December 22, 2014

Grammer
since "none" is singular, none of the choices is correct.
December 22, 2014

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

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