Thursday
November 27, 2014

Posts by steve


Total # Posts: 27,023

Physics
think on it. If the angle of elevation is 0, a = 0 if x = 90 degrees, a = g So, what trig function has its zero at x=0, and its max at x = 90 degrees?
October 4, 2014

Algebra
If m play in marching band, then m+250-130 = 375 m = 255 How did you arrive at 135? I can see 125, but not 135. Anyway, the question was not "how many play only in the marching band?"
October 4, 2014

math
Let x be the number of 10-person increases. So, since revenue is price*people, R(x) = (200+10x)(30-1.50x) That is just a parabola, with its vertex midway between the roots, at x = (-20+20)/2 = 0 That is, max revenue for just 200 people. That is assuming that the price decrease...
October 4, 2014

Algebra
3*85 <= 83+91+x <= 3*90 255 <= 174+x <= 270 81 <= x <= 96
October 4, 2014

Algebra
correct. But I suspect that was not really the question. If the question was asking for P', then that would be {2,4,6,8} When talking about sets, it's better to use the braces; otherwise, you just have a list, not a set.
October 4, 2014

Algebra
Hmmm. You think 5 is a factor of 16? If so, you need to review the term "factor". Better prune your list a bit.
October 4, 2014

AP Statistics
From the Z table, the 10% tail is 1.282 std from the mean. Since the 10% tail is used on both ends, the mean is halfway between where the tails start. That help?
October 4, 2014

algebra
x=1, y=2: x+y=3, 3x+2y=9 (8)(9)(x+y)/(3x+2y) = 24
October 4, 2014

Science
correct again.
October 3, 2014

Physics
Oops -- v = -9.8t
October 3, 2014

Physics
horizontal speed is constant: 30.9/3.03 m/s The vertical speed is v = at = -4.9t The angle x is such that tan(x) = Vy/Vx
October 3, 2014

Physics
the height is h(t) = 20.7t - 4.9t^2 That's just a parabola; the max height is at the vertex. Now just solve for t when h=0. To save yourself some work, the max height is reached at the center of its flight, so you really only need to calculate one of the above answers, ...
October 3, 2014

Science
You are correct.
October 3, 2014

math
6^2 = 36 1+3+5+7+9 = 25 + 4 = 29 2^5 = 32
October 3, 2014

math
200 * 0.1 = ? Ever hear of a calculator?
October 3, 2014

Math
True, but we also have (a+9)(a+16) = a^2 + 25a + 144
October 3, 2014

one last difference (math)
I think you need to reword your question. 1.2 is the fraction less than 1.8 Now, if you want to know how much less than 1.8 1.2 is, then of course that would be 1.8-1.2 = 0.6
October 3, 2014

math
So, did you use the table?
October 3, 2014

math 156
P(1+.04/4)^(4*6) = 35000 Now just solve for P.
October 3, 2014

math
Just match the values in pairs. A. Each pair adds up to 1002 B. Each pair adds up to 100 Now just figure out how many pairs there are.
October 3, 2014

algebra 2
x=9 2x+3y = 30 Now the rest of the questions get easier.
October 3, 2014

pre-calc
Clearly, since we have a semicircle, the width of the rectangle is half the length. So, A = (3x/2)(3x) P = 2(3x/2 + 3x)
October 3, 2014

Physics
If you are not familiar with the equations for trajectories, the wikipedia article for that subject has a good treatment. Just plug in your values for the equation of motion, and crank it out. If you get stuck, come on back with your work so far, and we can give you a nudge in...
October 3, 2014

Math
In that case, review your basic trig functions. cos(x) = 7/21 Now just find x, with that value for cosine.
October 3, 2014

Pre-Calc/Trig...
No idea. But the answer is clearly B, if for no other reason than that x and y have opposite signs on the left.
October 3, 2014

Pre-Calc/Trig...
recall the point-slope form of a line. In this case, y-1 = 3(x-10) Now massage that into one of the choices.
October 3, 2014

houston community college
Since PV=kT, PV/T is constant. So, since P is constant, V/T is constant. That means: 1.4/(27+271) = V/(177+271)
October 3, 2014

Calc
I don't know what the original problem was, but if the doubling time is 24 days, the formula for the amount present after t days is A(t) = Ao * 2^(t/24) Since 2 = e^ln2, that is equivalent to A(t) = Ao * e^(ln2/24 t)
October 3, 2014

AP CALC. AB
f(x) = 3/x f'(x) = -3/x^2 So, we want -3/c^2 = 3(-3/4) c^2 = 4/3 ...
October 3, 2014

calc
when t=0, Q=0.414 = a e^.885 = 2.423, so Q = .414(2.423^t) population grows by a factor of 2.423 every period. well, duh: k = 0.885 = 88.5%, though it's not usually expressed as a percent. Actually, that's k if you express Q as a e^kt
October 3, 2014

trig
sin(x) = 12/15, so ...
October 3, 2014

Pre-Calculous
.887 = e^-.1199, so .887^1.2t = e^(-.1199*1.2t) = e^-.144t It's always better to show your work, so we can help correct the errors, if any.
October 3, 2014

AP Calc. AB
when the tangent passes through the origin, it is of the form y = kx So, we want places where the slope is y/x. y' = 20x^4 - 12x^3 + 30x So, we want places where 20x^4 - 12x^3 + 30x = (4x^5-3x^4+15x^2+6)/x That is, where 20x^5-12x^4+30x^2 = 4x^5-3x^4+15x^2+6 16x^5-9x^4+15x...
October 3, 2014

CALCULUS
you want 1.043^t = 2.0 t log 1.043 = log 2 t = log2/log1.043 = 16.5 years This is roughly in accordance with the rule of 72: 72/4.3 = 16.7
October 3, 2014

Math
since cot(z) has asymptotes at all multiples of pi, h(x) above will have asymptotes at all places where x/2 is a multiple of pi.
October 3, 2014

Physics
Two satellites, A and B, are in different circular orbits about the earth. The orbital speed of satellite A is eighty-two times that of satellite B. Find the ratio (TA/TB) of the periods of the satellites.
October 3, 2014

English
yes and yes
October 3, 2014

math
The size of the cut will not, of course, change the length of the board. It will, of course, affect the total length of the cut pieces, since 1.25" will be lost after 10 cuts. I suspect there is more to this problem than what you asked, but if you want answers, you have ...
October 3, 2014

geometry
That would be 672 - (-36) = ?
October 3, 2014

math
If $x go at 2%, the rest (4000-x) is at 5%. So, add up the interest on each part: .02x + .05(4000-x) = 155.00
October 3, 2014

algebra
If the plane's speed is p, and the wind's speed is w, then since distance = speed * time, 3(p+w) = 1500 3(p-w) = 1380 Now you can easily find p, and then w.
October 3, 2014

Math
yes.
October 3, 2014

physics
total distance: 15.9+25.3+34.3 = 75.5 mi total time: 15.9/51 + 25.3/41 + 34.3/38.6 = 1.82 hr So, avg speed is 75.5mi/1.82hr = 41.55 mi/hr
October 3, 2014

Math
no - that fixed fee of $32 wrecks the proportion.
October 3, 2014

Math
First, the income in 2010 is not P(10), it is P(3). P(t) is only defined for 2<t<6, where t is the years since 2007. P(3) = 6(3)-24 = -6, so P(t) is decreasing there. Note that P'(t)=0 when t=4. That means it is decreasing more slowly until t=4, then starts to ...
October 2, 2014

Calculus
You have the right idea, but y' = 1 - 1/(2√x) Setting that to zero, we get 1 - 1/(2√x) = 0 1/(2√x) = 1 2√x = 1 √x = 1/2 x = 1/4 As you can see from the graph, there is only the one point (1/4,-1/4) with a horizontal tangent. http://www....
October 2, 2014

Math
Do you know what the midpoint is? It is the point midway between A and C. That is, it is the same distance from A as it is from C. That is, AB = BC
October 2, 2014

Calc
both wrong. Better review the definition of continuous. sin(x)/x -> 1 as a limit as x->0, but 0/0 is not defined, so it is not continuous there.
October 2, 2014

Math
p = (74.5+124.2)/242 p is not 1.0, because of things called divorce and death.
October 2, 2014

physics
since the distance s = vt + 1/2 at^2, 4780*525 + 525^2/2 ax = 3.54*10^6 8850*525 + 525^2/2 ay = 7.77*10^6
October 2, 2014

math
For F(x,y) = 3y cosx, we have Fx = -3y sinx Fy = 3 cosx Fxx = -3y cosx Fyy = 0 Fxy = -3 sinx So, for a saddle point, we need Fx = 0 true for x=0,pi or y=0 Fy = 0 true for x=pi/2, 3pi/2 and all y Fxx * Fyy - (Fxy)^2 < 0 -3y cosx * 0 - (-3 sinx)^2 < 0 true for all x. The ...
October 2, 2014

math
42
October 2, 2014

pre calculus
since d/F is constant, .15/265 = .2/x and, .165/265 = x/100 Note that you don't really have to find k, the constant of proportionality. You can go ahead and find it, but your answers will be the same.
October 2, 2014

math
approximate: use 30 days per month. exact: get a calendar.
October 2, 2014

Math
At x=2, x-5 < 0, so the slope at x=2 is just -1. Ok, ok, algebraically, f(2+h) = |2+h-5|-7 = |-3+h|-7 Since the value is negative, that will be 3-h-7 = -4-h f(2) = |2-5|-7 = 3-7 = -4 -4-h - (-4) = -h Now, divide by h and you have -h/h = -1
October 2, 2014

Math
pretty good, but you know that cot π/4 = 1 csc π/4 = √2, so m = -12(1)(2) = -24 So the line is y-3 = -24(x-π/4)
October 2, 2014

geometry
If the points are in a aline, then I expect AB + BC = Ac So, 9a + 12a = 42 21a = 42 a = 2 Now you can figure out the lengths AB and BC
October 2, 2014

Math (Implicit Differention)
of course, you can simplify that last result to just √3, since it is (3^(3/2))^(1/3) = 3^(1/2) Also, you dropped/gained a minus sign in there somewhere. The point is in QII, where the slope is positive.
October 2, 2014

calculus
x^2/3+y^2/3=4 2/3 x^-1/3 + 2/3 y^-1/3 y' = 0 y' = -(y/x)^1/3 So, at (-1,3√3), y' = -(3√3/-1)^(1/3) = √3 You can see the graphs at http://www.wolframalpha.com/input/?i=plot++x^%282%2F3%29%2By^%282%2F3%29%3D4+%2C+y+%3D+-%E2%88%9A3%28x-1%29+%2B+3%E2%...
October 2, 2014

Math - Please Check My Answer - Probably Last One!
the ratio is just (πr^2h) / (2r)^2*h πr^2h / 4r^2h π/4
October 2, 2014

Math - Please Check My Answer
D is correct. In A, 3x^0 = 3*1 = 3, while (3x)^0 = 1 (assuming x is not zero)
October 2, 2014

AC DC Circuit fundamentals
since they are in series, the voltage drop is divided up into 2/3 across the 10k 1/3 across the 5k since R = R1+R2 = 5+10 = 15 k, and 10 is 2/3 of 15, 5 is 1/3 of 15.
October 2, 2014

Trigonometry
f(x-a) is f(x) shifted right by a. So, yours is shifted left by 5. f(x)+k is f(k) shifted up by k.
October 2, 2014

Math
4(x+15) >= 120 x+15 >= 30 x >= 15
October 2, 2014

Math
3/2 + 23 since max of sine is 1.
October 2, 2014

Math
right again.
October 2, 2014

Math
both correct!
October 2, 2014

Trigonometry
since the maximum of sin(x) is 1, d(t) achieves a maximum of 3/2 + 23.
October 2, 2014

Math
Just do hex long division, as at http://mathforum.org/library/drmath/view/63375.html However, it is sometimes easier to convert to decimal, divide, and convert back.
October 2, 2014

Algebra ll
division by zero is not defined. What is 12/0? 0/0? So, for a rational function, the domain excludes any values where the denominator is zero, because the domain is the set of values of x for which f(x) is defined. For f(x) = (x^2 - 25)/2 the domain is all real numbers; there ...
October 2, 2014

Simplify this Expression?
You can do it using the distributive property as J and Ms Sue did, or you can use it implicitly, working term by term z-2z+4z+6 -z+4z+6 3z+6 Their answers basically factored out the z, as in z-2z+4z+6 (1-2+4)z+6 (3)z+6 3z+6
October 2, 2014

geometry
think of alternate interior angles, or consecutive interior angles.
October 2, 2014

Trigonometry
Just do things as you normally would. tan 28 = 0.5317, so you have (20-x)/6.11 = 0.5317 20-x = 3.25 x = 16.75 Don't forget your algebra I just because you're taking trig now!
October 2, 2014

math
Looks to me like .013
October 2, 2014

Plane and Spherical Trigonometry
Use the law of cosines. The third side can be found using AC^2 = 20^2 + 35^2 - 2(20)(35)cos(180-80)°
October 2, 2014

math
(g-48)(g-20) = 480 g = 60 So, the grandfather is 60. ...
October 2, 2014

Math
1/4 * 1/2 = 1/8
October 2, 2014

math
(14 - (15/3))/2 = 9/2
October 2, 2014

English - Parts of Speech
a simple google search will provide numerous examples.
October 2, 2014

maths
sorry, no diagrams here. But I bet you can do it. Just look in your text (or online) for similar situations, and change the numbers. You just have to draw two intersecting circles.
October 2, 2014

algebra
7 + 2x
October 2, 2014

Physics
A 0.60-kg basketball is dropped out of the window that is 6.1 m above the ground. The ball is caught by a person whose hands are 1.2 m above the ground. (a) How much work is done on the ball by its weight? (b) What is the gravitational potential energy of the basketball, ...
October 2, 2014

Physics
The drawing shows two boxes resting on frictionless ramps. One box is relatively light and sits on a steep ramp. The other box is heavier and rests on a ramp that is less steep. The boxes are released from rest at A and allowed to slide down the ramps. The two boxes have ...
October 2, 2014

Math
as with all fractions, multiply top and bottom by the GCD (a-1)(b) to get 1/(a-1) + 1/b = c b + (a-1) = c(a-1)(b) b + a - 1 = abc - bc a - abc = 1 - b - bc a = (1-b-bc)/(1-bc) = 1 + b/(bc-1)
October 1, 2014

Precalculus
If the width surrounding the rug is w, then (12-2w)(16-2w) = 12*16/2 Now just solve for w and determine the rug dimensions.
October 1, 2014

calculus
The curves intersect at (4,0) and (1,3). You don't specify the axis, so, assuming the x-axis, using shells, the volume is v = ∫[0,3] 2πrh dy where r = y and h = (5-(y-1)^2)-(4-y) v = 2π∫[0,3] 3y^2 - y^3 dy = 27π/2 Using washers, we have to break ...
October 1, 2014

Algebra HELP!
No ideas on any of them? Look for groupings of like expressions, difference of two squares, etc. For example, (g) is (x^2-y^2) + x + y (x-y)(x+y) + (x+y) (x-y+1)(x+y)
October 1, 2014

Algebra
Looks good to me. I tend to avoid fractions where possible, so I'd probably have done it as 42+48+x = 3*47
October 1, 2014

Math
(6+2w)(12+2w) = 520 w = 7
October 1, 2014

Math help!
(-2)^n+2n: -2+2, 4+4, -8+6, 16+8, ... n^2(-1)^n: -1, +4, -9, ... |10-n^2|: |10-1|, |10-4|, |10-9|, ...
October 1, 2014

Math
nope - that fixed fee of $32 wrecks the proportion.
October 1, 2014

Math
the length is clearly 36 cm The pieces can be (36/9)x26 or 36x(26/9) Assuming you want integer dimensions, I'd go with the first choice.
October 1, 2014

Math
68*3 + x = 70*4 you want large on top and small on bottom, so 984/12
October 1, 2014

Algebra
what, you have a problem evaluating expressions? (-2)^n+2n: -2+2, 4+4, -8+6, 16+8, ... n^2(-1)^n: -1, +4, -9, ... |10-n^2|: |10-1|, |10-4|, |10-9|, ...
October 1, 2014

algebra2/ trig
The centers of the pipes form an equilateral triangle, with sides of length 24. The belt then consists of three straight segments of length 24, and three arcs of the circles, subtending angles of 2pi/3.
October 1, 2014

algerbra 1
Strange language; I suspect you meany "by" 15, so on that basis, we have 2x = 3(x+4)+15 -x = 27 x = -27 and the numbers are -27 -25 -23 check: -54 = -69+15
October 1, 2014

Math
yes - just divide as shown 7/3 = 2.33 3/4 = 0.75 and so on
October 1, 2014

Math
#1 ok #2 - the discount was 15%, meaning the actual price was 85%, so 0.85p = p – 150 #3 WHAT? They just told you that A traveled 22 mph faster than B! If car B has speed s, then 2.4(s+22) = 4s This will give you B's speed. The distance traveled was 4s #4 If the ...
October 1, 2014

Math help!
clearly, at a change rate of -20 per year, (a) -20(5) = -100 (b) -20(-5) = +100 (c) -20n (d) -20(-n) = +20n
October 1, 2014

Trig
The first plane ends up at (169.7,-169.7) The other plane ends up at (-205.1,-205.1) So, relative to the first, the second plane is at (-374.8,-35.4) arctan(-35.4/-374.8) = 185.4°, or W5.4°S
October 1, 2014

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