Saturday
October 25, 2014

Posts by STEVE


Total # Posts: 26,094

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

Chemistry/Math
ppm of what? .01403g is just a mass. That's not much to go on
October 1, 2014

Algebra
just write each sentence in symbols, then solve the equations. #1 Maria has 105+10m Jana has 0 + 25m So, we want 105+10m = 0 + 25m Now just solve for m and then the amounts #2 There's a rental rate of r, and a late fee of f, so Nate: r + 1f = 5.50 Gina: r + 4f = 10.00 Now ...
October 1, 2014

Math-G7 Help please
#1 d = b+4 d+b = 22 #5 w(x+y) = 126 y = 2x #8 d+q = 20 10d+25q = 275 #15 s+a = 421 2s+5a = 1244 #17 b = s/3 b+2s = 84 Just translate each sentence into symbols.
October 1, 2014

Math
4(0) + 1(-3) + 1(-6) + 4x = 63 Now just solve for x
October 1, 2014

math
change in speed = 8 m/s at 2(m/s)/s, that will take 8/2 = 4 seconds
October 1, 2014

Algerbra math
(7+2)x^2 + (3+5)x + (9-2) That should help.
October 1, 2014

Math
any number bigger than the square root of Dalton's area.
October 1, 2014

math
to find y(x) for a specific x, just replace each x with its value. (a) y(-1) = -3(-1)-2 = 3-2 = 1 and so on (d) -a = -1(a) (e) just solve for x in -3x-2 = -11
October 1, 2014

College algebra
if there were x reserved seats, then the rest (40000-x) were general admission. So, adding up all the ticket prices, we get 12x + 5(40000-x) = 298000 x = 14000
October 1, 2014

Math- Multi-step word problems
3(s+20) = 3.20(s-20) s = 620 3*640 = 1920 3840/(3 + 3.20) = 619.35 so you are correct
October 1, 2014

Math- Multi-step word problems
d/(10-3) = d/(10+3)+1 so you are correct
October 1, 2014

Math- Multi-step word problems
If the plane's speed is s, then since distance = speed * time, 4(s+10) = 4.15(s-10) That gives s=543.33 553.33*4 = 2213 533.33*4.15 = 2213
October 1, 2014

Math--1 question
well, you can surely see that 56+c = 83 It's easy to find c, and it's not 33.
October 1, 2014

Trigonometry
Draw another line making an angle of 28°, passing through the tip of the overhang to the wall. If the height of sunlight on the wall is x, then (20-x)/6.11 = tan 28°
October 1, 2014

math
that depends on the tools you have at your disposal. Some curves have special properties, like the vertex of the parabola ax^2+bx+c is at x = -b/2a, and so forth. If you have access to calculus, you can find minima on a wider variety of curves. The most general tool would be a...
October 1, 2014

math
45(.80 - 1/3) = 21 The tank was not full at the beginning of the month, but only 80% full, or 36 gallons.
October 1, 2014

Maths
693 = 3^2 7 11 1365 = 3 5 7 13 The highest powers of all the primes in both lists are 3 7 so the GCF is 21
October 1, 2014

Math Multiplication
Just start trying divisors: 1 642 2 321 3 214 6 107 Since 642 = 2*3*107, that is all the factors there are
October 1, 2014

math
old diameter: d old area: pi/4 d^2 new diameter: 1.5d new area: pi/4(1.5d)^2 = pi/4 d^2 (2.25) So, new area - old area = 2.25-1 = 1.25 = 125%
October 1, 2014

math
hmmm. Looks like (54.28 - 48.70)/2 = 2.79 inches why the /2 ?
October 1, 2014

Trigonometry
as usual, amplitude = 1/2 period = 2π/π = 2 The - sign doesn't mean anything here, since cos(-x) = cos(x)
October 1, 2014

Trigonometry
C'mon. If 2π/k = .004, k = 2π/.004 = 500π
October 1, 2014

Trigonometry
this is just the other problem in reverse. Why not give it a shot? You know that the period of sin(kx) is 2π/k... Also, period = 1/frequency
October 1, 2014

Trigonometry
amplitude = 3 period = 2π/1 = 2π
October 1, 2014

math
Just looking at the formula, you could surely see that 10 is wrong, because then the area would be 100π = 314, not 658. So, πr^2 = 658 r^2 = 658/π = 209.4479 r = 14.47
October 1, 2014

physics
If the boat's speed is s, and the river's speed is r, and the boat is traveling east (0 degrees), (0,r) + (s cos297,s sin297) = (6,0) now just solve for r and s.
October 1, 2014

math
(6x^3+13x^2+6x+158)/(3x+11) = 2x^2-3x+13 R 15 If that was supposed to come out even, I suspect a typo. I guess you will have to figure out why NCC is important.
October 1, 2014

Pre-Calculus/Trig...
Surely you can graph both those simple functions. Just switch from one to the other at x=1. since 0 < 1, f(0) x^2 = 0.
October 1, 2014

College Alg
P(x) = R(x)-C(x), so just solve for x in x(50-.002x) - (12x+150000) = 1650000 I suspect a typo, since that has no real solutions.
October 1, 2014

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Search
Members