Monday
February 8, 2016

Posts by steve

Total # Posts: 37,488

math
floor: 12*10 long walls: 2(12*8) short walls: 2(10*8) Now add 'em up.
February 8, 2016

Math
29.95/1.02 = ?
February 8, 2016

physics
see related questions below
February 8, 2016

Math
1B Can you not tell that by looking at the figure? 2B a square is a rectangle with 4 equal sides. 3B just look at the letters, keeping them in the same order.
February 8, 2016

Math
apparently her notation is ^. for * meaning multiply. Trés strange.
February 8, 2016

math
First, that's pi not pie!!! Just start subtracting 2pi from your angle until the result is between 0 and 2pi. 3pi - 2pi = pi we have a winner!
February 8, 2016

maths
When asking how much one value is than another, you just subtract. If I ask How much bigger 10 is than 3, you do 10-3=7. So, (-39)-(-98) = -39+98 = 59
February 8, 2016

math
well, did you try actually verifying it? (5/8)(-3/5) + (1/16)(-3/5) = -15/40 - 3/80 = -33/80 3/16 - 3/5 = 15/80 - 48/80 = -33/80 I guess your answer is correct.
February 8, 2016

Math
If there are x lbs, each one gets x/3 so x >= 10.5 x/3 >= 3.5
February 8, 2016

Algebra
105 mi/hr = 154 ft/s So, it takes 60.5/154 seconds
February 8, 2016

Math
the independent variable is the one which you can set to whatever you want: in this case, the number of students. Since there is a fixed cost for each student, the cost depends on the number of students.
February 8, 2016

MATH
5x + 4.20(26-x) = 4.80*26
February 8, 2016

MATH
stop posting problems which refer to a pictures we cannot see.
February 8, 2016

math
3^x * 5^x + 1=20 (3*5)^x = 19 15^x = 19 x = log1519
February 8, 2016

Math
hard to say, with no picture to see.
February 8, 2016

Math
area grows as the square of the sides. So, the areas are in the ratio (2/3)^2 = 4/9
February 8, 2016

Math
If you mean of a circle, it is that portion of a circle subtended by a central angle. That is, if two radii are drawn, the sector is the area between them.
February 8, 2016

Maths
(22^3 * 7/8)/(π/6 * .5^3) ≈ 142,353
February 8, 2016

math
p(w) = 7+2w
February 8, 2016

Calculus (double integral) PLEASE HELP!
This exact transformation is discussed on pp 3-5 of http://math.etsu.edu/multicalc/prealpha/Chap4/Chap4-4/printversion.pdf
February 8, 2016

Math
p(t) = 157354 * 2^t
February 8, 2016

math
One way is elimination, where you multiply the equations to enable addition to eliminate one variable: 6x+4y = -36 -6x+15y = -78 now if you add them up you get 19y = -114 Thus, having y, you can now get x from either equation.
February 8, 2016

math
the area of the border is (500)(130)-(500-2*25)(130-2*25) = 29000 cm^2 Now you can find the cost
February 8, 2016

trigonometry
Remember the Pythagorean Theorem? The distance d is d^2 = 200^2 + 60^2
February 7, 2016

Calculus (Jacobian question)
This type of problem is discussed on pages 3-5 at http://math.etsu.edu/multicalc/prealpha/Chap4/Chap4-4/printversion.pdf
February 7, 2016

Math
mass of pure gold would be 5*18*4 cm^3 * 19.3 g/cm^3 = 6948g so, what do you think?
February 7, 2016

calculus
∫ x^3/√(3x^2-5) dx x = √(5/3) secθ 3x^2-5 = 5tan^2θ dx = √(5/3) secθ tanθ dθ and the integral becomes ∫ √(5/3)^3 sec^3θ/(√5 tanθ) √(5/3) secθ tanθ dθ = 5/9 √5 ∫sec^4&#...
February 7, 2016

physics
oops. the horizontal speed is 33.437 cos20° make that fix...
February 7, 2016

physics
h(t) = vt - 1/2 g t^2 3.5v - 4.9*3.5^2 = -20 v = 11.436 That v is the vertical speed at takeoff. So, the entire initial speed is 11.436/sin20° = 33.437 Use that speed and d = vt to get the horizontal distance traveled. d = 33.437 * 3.5 = 117.028
February 7, 2016

Precalculus
Huh? Forget your Algebra I? Anyway, just type in your function at wolframalpha.com
February 7, 2016

Trigonometry
Draw a diagram, and you will see that x cot14° + x cot18° = 55 x = 55/(cot14° + cot18°)
February 7, 2016

math
.42
February 7, 2016

Algebra
u = kp^3/d
February 7, 2016

Algebra
add up the value of the parts: 8.40x + 14.70(70-x) = 14.61*70 Expect a value of nearly zero for x, since the price of the mix is very close to the price of the Mexican coffee.
February 7, 2016

Calculus
The paraboloids intersect along an ellipse 3x^2+2y^2 = 6 So, the volume is (using symmetry) v = 4∫[0,√2] ∫[0,√((6-3x^2)/2)] (6-x^2-y^2)-(2x^2+y^2) dy dx = 3π√6
February 7, 2016

math
you are right
February 7, 2016

Math
You are correct.
February 7, 2016

Numericals
v = √2as = √(2*9.8*15) = 17.146 m/s Since the ball's energy PE = mgh, if it loses 40% of its energy, it will lose 40% of its height, so it will bounce to 9 m. Or, since PE becomes KE just before impact, KE = 1/2 mv^2 The rebound velocity will be .6 * 1/2 m*17....
February 7, 2016

calculus
see related questions below.
February 7, 2016

radicals
just multiply roots like anything else. If a square root contains a perfect square, like 16 or 49, you can factor the 4 or 7 out of the root. For this problem, √8(√(9ab)/√(3b) + √(27a)) 2√2 (√(9ab/3b) + 3√(3a)) 2√2 (√(3a...
February 7, 2016

calculus
a = (90-30)/10 = 6 km/hr-s s = 1/2 at^2 = 3 km/hr-s * (10s)^2 = 300 km-s/hr = 300 km-s/hr * 1hr/3600s = 300/3600 km = 1/12 km or, since you want to use calculus, a = 6km/hr-s = 6km/hr-s * 1hr/3600s = 1/600 km/s^2 so, a(t) = 1/600 v(t) = 1/600 t s(t) = 1/1200 t^2 s(10) = 100/...
February 7, 2016

math
if compound interest, 400(1+r)^4 = 480 (1+r)^4 = 1.2 r = .0466 Is your new r (r + .02)=.0666 or is it 9*1.02 = .0475 ?? Do a similar calculation if simple interest.
February 7, 2016

Math
f(x) = √(x-2) You know that the domain of √x is x>=0. So, you need x-2 >= 0 Not too hard, eh?
February 6, 2016

maths
well, sin(x) = 125/250 = 1/2 look familiar?
February 6, 2016

Maths
If you draw a careful diagram, you will see that the altitude is 240cm between the bases. Using similar triangles, you can see that if the pyramid were not chopped off, its height would be 320/3. So, the missing part is a pyramid of base side 80 and height 400/3. Now just work...
February 6, 2016

Linear Algebra
First, be sure you understand a matrix null space. Google is your friend. Te null space is all vectors x such that xA = 0 I'm having a hard time understanding A[1, 1, 1]^t = [2, 3]^t = A[2, 3, 4]^t How can they all be equal?
February 6, 2016

Calculus
Just integrate a = ∫[-1,0] (13-5x)/3 - (-6x) dx + ∫[0,2] (13-5x)/3 - x/2 dx = 13/6 + 13/3 = 13/2 Or The distance from (0,0) to (1,2) is √5. Let that be the base of the triangle. The altitude is the distance from (-1,6) to y=x/2 (or -x+2y+0=0) is |1+12|/√...
February 6, 2016

Physics 30
see Coulomb's law.
February 6, 2016

Physics 30
since only one current is given, I'll assume the R are in series E = IR, so 22 = .012(27+R)
February 6, 2016

Physics 30
come on, that's ohm, not omega. Omega is just the symbol used for the unit. 1A = 1C/s P = I^2R = (10/5)^2 * 25 = 100 W energy = power * time
February 6, 2016

Physics 30
since the force is inversely proportional to d^2, it will be reduced by a factor of 25.
February 6, 2016

PHYSICS
Coulomb's law is discussed here: http://www.physicsclassroom.com/Class/estatics/U8L3b.cfm just plug in your numbers.
February 6, 2016

physics & math
well, recall that v = √(2as) so, plug in your a and s.
February 6, 2016

Calculus (polar coordinates)
recall that dA = r dr dθ so, since x = r cosθ you have ∫[0,π/2] r cosθ r dr dθ = ∫[0,π/2] r^2 cosθ dr dθ But, r changes at π/4, so that gives ∫[0,π/4]∫[0,2sinθ] r^2 cosθ dr dθ + ∫[&#...
February 6, 2016

Math
Hmm. I'm still unclear. What is an example where switching the hands is invalid?
February 6, 2016

Math
Do you mean the physical clock hands are switched? No problem. I mean, the hands still point to places on the dial, right? If you mean the digital time has hh:mm swapped to mm:hh, then any time from 01:01 to 01:12 is ok and so on for the other hours. As long as the minutes are...
February 6, 2016

Math
<head slap> dontcha hate it when that happens? Still, the aha! moment is worth the pain.
February 6, 2016

Math
recall that the y-intercept is where the line crosses the y-axis. The line y=16 clearly crosses the y-axis at y=16, because it is 16 for any value of x, in particular, x=0.
February 6, 2016

calculus
The curves intersect at (0,0) and (3,9) So, rotating around the x-axis, using discs: v = ∫[0,3] π(R^2-r^2) dx where R=3x and r=x^2 v = ∫[0,3] π((3x)^2-(x^2)^2) dx = 162π/5 shells (tubes): v = ∫[0,3] 2πrh dy where r=y and h=(√y)-(y/3...
February 6, 2016

Physics
A: since the initial v=0, only g is acting on the mass. B: ok C: D = bv^2 = b(√(mg/b)/2)^2 = mg/4 SO, net a = mg/4 - mg = -3/4 mg
February 6, 2016

Pre-Calculus
looks good to me. You can always check your answer by typing in the polynomial at wolframalpha.com
February 6, 2016

Pre-Calculus
enter your coefficients at http://www.mathportal.org/calculators/polynomials-solvers/synthetic-division-calculator.php Looks like you goofed somewhere.
February 6, 2016

Do I have time
no, but google shows many hits, the first at (wow!) biography.com
February 6, 2016

Do I have time
Sure you have time. 3 days for 4 more paragraphs? No sweat, if you get to work. Of course, judging by your posting, you have some serious proofreading to do ...
February 6, 2016

algebra 2
the domain for all polynomials is (-∞,∞) Think about it -- pick any value of x and you can calculate f(x).
February 6, 2016

algebra
At first I thought your work was a hodgepodge, but further study shows that you are correct. except that 95/7 is not 13. Should have been 91, so you messed up somewhere.
February 6, 2016

Calculus
No, at 20 mi/hr, every mi/hr increase in speed decreases the fuel consumption by .05 gal/hr. Keep track of the units. Seems kind of odd though, that rate of fuel consumption decreases with increasing speed...
February 6, 2016

Calculus
#1 ok #2 f' = dc/dv = (gal/hr)/(mi/hr) = gal/mile #3 sort of - see units for #2.
February 6, 2016

Math Radicals
just expand like normal binomial multiplication: (a+b)^2 (2√5+3)(2√5+3) = (2√5)^2 + 2(2√5)(3) + 3^2 = 4*5 + 12√5 + 9 = 20 + 12√5 + 9
February 6, 2016

math
p(t) = 4i+8j + (4i+j)t q(t) = 4i+3j + (2i+5j)t the distance pq is d(t) = p(t)-q(t) = 5j + (2i-4j)t = (2t)i + (5-4t)j |d| = √((2t)^2 + (5-4t)^2) = √(20t^2-40t+25) Hmmm. I get √5 as the minimum distance. Better check my math.
February 6, 2016

Mathematics
8x^3 = 0
February 6, 2016

Math and Physic
Right off, I'd say the building has zero velocity. as for time to fall, h - 4.9t^2 = 0 plug in t= 7.57
February 6, 2016

Calculus
If the width is x and the rectangle's height is y, then x+2y + π/2 x = 24 so, y = (24-(1+π/2)x)/2 The area is a = xy + π/2 (x/2)^2 = x(24-(1+π/2)x)/2 + π/8 x^2 = 12x - (1/2 + π/8)x^2 Now just set da/dx=0 to find where the max occurs. Or, use ...
February 6, 2016

sinusoidal functions
The central axis is at y = 5 y = sin(x)+5 Two consecutive minima are found at (3, −1) and (13, −1) So, the period is 10, the amplitude is 5+1=6, and the shift is 3. cos has max at x=0, but we have a minimum, so y = -6cos(π/5 (x-3))+5 see the graph at http://...
February 6, 2016

math
rear legs get 2/3 and front get 1/3 now divide those amounts by 2, since there are two front and two rear legs.
February 6, 2016

calc
f'(p) is the rate of change of quantity as price changes Think of the units: f is yards p is dollars, so df/dp = yards/dollar no idea whether f'(16) is positive or negative. However, it is likely that as price goes up, demand goes down.
February 6, 2016

system of equations
a + 30b = 1300 a + 80b = 2200
February 5, 2016

Calculus
looks ok to me y = f^3(g(x)) dy/dx = 3f^2 df/dg * dg/dx for example, y = sin^3(x^2+1) dy/dx = 3sin^2(x^2+1) cos(x^2+1) (2x)
February 5, 2016

Linear Algebra
depends. what is b? As long as the matrix has a nonzero determinant, there will be a solution.
February 5, 2016

Math
Looks more like A to me.
February 5, 2016

Geometry
google online drawing tools. Or, hey! How about this idea? Go Buy Some Graph Paper! Actually, there are online sites which have graph paper you can print.
February 5, 2016

Maths
review the cotangent function. Draw a diagram and you will see that the distance the plane has flown is 880 cot24°30' - 880 cot67°40'
February 5, 2016

math
2a+3c = 44.40 3a+6c = 78.00 That's the same as 2a+3c = 44.40 a+2c = 26.00 subtract and you get a+c = 18.40 Note that we don't actually have to find the price of the individual tickets.
February 5, 2016

Geometry
#1 ok. #2 you figured the length of the hypotenuse. The perimeter is 9+12+15 = 36.
February 5, 2016

math college readiness
h(t) = 105 - 9t - 16t^2 When does it hit the ground? That would be when h(t) = 0, right? So, just solve the quadratic equation.
February 5, 2016

Math
If they are linear equations, it is A. Parallel lines (same slope) never intersect. But lines with different slopes must intersect somewhere.
February 5, 2016

Math
you are correct.
February 5, 2016

math
If the unknown force is x, then you just need to solve 550 - 300 + x = 0 because the sum of all the forces needs to be zero. I think that once you get your answer you will (a) see why the given formula works (b) notice the typo as written
February 5, 2016

math (sequence and series )
salary: 1st 8 years: 240 years >= 9: Tn = 9500+360(n-8) Total after 8 years: 8*240 = 1920 n years: (n > 8) Sn = (n-8)/2 (2*9500 + (n-9)*360) So, plug in your numbers for n
February 5, 2016

Physics
if the graph shows the actual error, just divide that by the correct value. For example if the correct value is 20, and the error is 3, then the percent error is 3/20 = 0.15 = 15%
February 5, 2016

precal
we can pick any direction for the 1st 3 blocks. Say, North. After the 1st 3 blocks N, E and W are interchangeable. Clearly, going N then S will not help, so she can do one of the following: E for 2, N for 1 E for 2, W for 1 E for 2, S for 1 I think you can tell which gives the...
February 5, 2016

Physics
well, uh, g, just read off the slope and equate it to 1/2 g: 5.00 = 1/2 g g = 10.00
February 5, 2016

Math
If each line represents 100 sales, then you are correct.
February 5, 2016

chemistry
wikipedia has a nice article on calcium, and lists several compounds which are essential for good health. Calcium always forms ionic bonds.
February 5, 2016

Math
Unless it's a large glass, I'd use ounces. Most glasses are 8-12 oz. Of course, those are fluid ounces. Plain ounces are a measure of weight, not volume. A fluid ounce is the volume occupied by one ounce of water.
February 5, 2016

MATH
google is your friend. I can tell you how, but you can find many illustrated instructions online. Place compass at one end of line segment. Mark an arc with radius more than half the line length. Do the same at the other end. Make sure the arcs are long enough to intersect in ...
February 5, 2016

Physics
The basic requirement for destructive interference is that the two waves be shifted by half a wavelength. Now, as you know, v = λν, so just plug in your numbers.
February 5, 2016

Math
just write that in symbols: nth denominator is 3^(n-1) nth numerator is 3^(n-1) - 2 So, the ntheterm is Tn = (3^(n-1) - 2)/3^(n-1) That can be massaged in various ways: Tn = 1 - 2/3^(n-1) Tn = 1 - 6/3^n Tn = (3^n - 6)/3^n
February 5, 2016

shuluka
Hora aderat briligi. Nunc et Slythia Tova Plurima gyrabant gymbolitare vabo; Et Borogovorum mimzebant undique formae, Momiferique omnes exgrabure Rathi.
February 5, 2016

Complex number
recall that (a+bi)(a-bi) = a^2+b^2 (1-i)/(1+i) * (1-i)/(1-i) = (1-i)^2 / (1+1) = (1-2i+i^2)/2 = (1-2i-1)/2 = -2i/2 = -i or, 0 - i
February 5, 2016

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