Wednesday
July 30, 2014

Posts by STEVE


Total # Posts: 24,029

algebra1
I get C

Geometry
The volume of clay is for a cylinder of radius r is pi r^2(0.75) + pi(r^2-(r-.4)^2)h = 206 Since we have r=4.5, h = 14.6 cm The base is easy, and just subtract that from 206 to get the lateral volume. The lateral surface is just 2pi r h

Algebra 2
cos(360-x) = cos(x) so, same as cos 60°

Math
for y = a cos(kx) period = 2pi/k amplitude = a

Algebra
y^2/9 - x^2/16 = 1 so, what are the foci of y^2/a^2 - x^2/b^2 = 1?

math Question
(1-3^10)/(1-3) = 29524

Algebra
x^2 = 4py where p = -4 So, ...

Please help w/ Algebra
because the perimeter is 56, 2w + 2l = 56 l + w = 28 l = 28-w

Please help w/ Algebra
If the field has width w, then the length is 28-w. (w-4)(28-w-4) = 91 w^2-28w+187 = 0 w = 11 The field is 11x17 The smaller area is 7x13 = 91

math Question
40/160 = r^2, so r=±1/2

Science
A person roller skates down a street heading West. What is true about friction in this case? the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward my answer is # 4

algebra 2
#1 ok #2 is 80 or -80 b? #3 is a: P(2,3,4,5,6) = 5/6

Science
If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball? the choices are 0N 3N 6N 12N I think its 6N

Algebra 2
If xy is constant, it's inverse If x/y is constant, it's direct Looks like (b) to me (c) is a bogus answer in any case.

math
you are correct.

math!
15*12 = 180 330-180 = 150 150/14 = 10 remainder 10

Multiple Choice
correct

Science
the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward

Science
A person roller skates down a street heading West. What is true about friction in this case?

Science
answers to chose from are 0N, 3N, 6N, 12N

Science
If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball?

math
1260(1-cos20°)

Trig
x^2+11^2 = 24^2 now just solve for x

maths
1260(sin30°)

math
depends. Is the same formula used for tv's and computers? If so, retail = 2*wholesale-75 wholesale = (retail+75)/2 so, plug in a retail price of $550

maths
a^-3 = 1/a^3 c^-1 = 1/c, so 1/(c^-1) = c^1 and we have bc/a^3

math
4 times the diameter, 16 times the area

Precal/trig
cos2a = 1 - 2sin^2(a) = 1 - 2*9/25 ... in this case, it doesn't really matter which quadrant a is in, as sin^2 is always positive. extra credit: which quadrant is 2a in?

math help !
Looks like D to me For #2, always check to see how much y changes when x changes by a fixed amount. That will give the slope of the line (the coefficient of the x term). Here, when x changes by +2, y changes by -1. So, the slope will be -1/2 and the function rule will look lik...

math
Better check B. It's the differences that are constant, not the ratios. A gives an exponential function. Consider y = 2^x when x grows by 1, y doubles. But, if y = mx+b (a linear function) when x grows by 1, y grows by m, and the difference is constant over equal intervals.

Calculus
you want to find c. So, since y(1) = 4, plug it in -1/(1^3+c) = 4 -1/4 = 1+c c = -5/4 Now the particular solution is y = -1/(x^3 - 5/4)

Calculus
You wan to find c, so plug in the point (-4,-1) which is on this particular solution curve: (-3*16)/(2+4+c) = -1 The way the function is worded makes me suspect a typo. Fix that, and find c for a particular solution.

Calculus
or, 2,000,000 = 10,000,000/5, so log 10^7 - log5 = 7-.699 = 6.301

Calculus
log2000000 = log 2 + log 10^6 = 6.301

help please
intraocular fluid is the answer I think

derivative
you can check your results at wolframalpha.com Just type "derivative" or "2nd derivative" and your function. Check to be sure it interprets your input as you intended. Parentheses are your friend. For your function, you correctly extracted the 9/e constant,...

Calculus
log(1000000x^19) = log(10^6)+log(x^19) = 6 + 19logx assuming logs base 10 :-)

Math help
Assuming ã means √, √338-√200+√162 = √169√2 - √100√2 + √81√2 = 13√2-10√2+9√2 = 12√2 Do the other in the same way: extract perfect roots, and combine the other factors under a single √

Math help
#1 -4√2+6√72-√32 = -4√2 + 6√36√2 - √16√2 = -4√2 + 36√2 - 4√2 = 28√2 #2 ok #3 12√13-74√2 remember that √8 = 2√2 #4 ok

math
correct except for the inconsistent capitalization

math
4! The fact that you are asking this question indicates that you are studying permutations. Surely it was explained in the text.

math
view it at wolframalpha.com This site will show you how to graph any function you care to enter. Play around some. http://www.wolframalpha.com/input/?i=1%2F3|x|-2+ Be sure to check to see how it interprets your input. It is pretty strict about using parentheses to alter the or...

math
If y = -2x^2 + 3, then just use the values of x and calculate the values of y: x y -3 -2(9)+3 = -15 -2 -2(4)+3 = -5 -1 -2(1)+3 = 1 0 -2(0)+3 = 3 1 1 2 -5 3 -15 Plot those points and sketch a smooth curve through them. Your graph should look like the one given by wolframalpha: ...

Mathematics
since the circumference of the ball is 2pi*11.5 = 72.26 cm, divide that into 2800cm to see how many times it rolls.

Algebra
add 5 to get the next terms.

Nice Save, MathMate
!!

algebra - typo?
I suspect a typo, since log3(√10+1)+log3(√10+1) = log3(10-1) = log3(9) = 2 the log7 of powers of 2 is not amenable to simplification. Is there a typo? At the very least, the parentheses are not balanced.

math
12 = 2^2 * 3 15 = 3*5 18 = 2*3^2 The smallest number which is a multiple of all of those must contain the highest power of each of the listed primes. So, that will be 2^2 * 3^2 * 5 = 180 But, we also want our number to be a perfect square, so we need to have 5^2 in the product...

Calculus
Judging from the graph at http://www.wolframalpha.com/input/?i=[3x^13]e^%28%E2%88%927x%29+for+x%3D0..3 I'd say it is concave down in that interval. In fact, since f"(x) = 3x^11 e^-7x (49x^2-182x+156) if the roots are where you say they are, then since the quadratic fa...

Calculus
concave down where f" < 0 better review your text, where it is surely explained and illustrated. f" < 0 means that the slope is decreasing. So, f is either rising either rising more slowly or falling more quickly. Consider a parabola which opens downward.

geometry
gain of what? perimeter will gain 10% area will grow by a factor of 1.1^2 = 1.21, or 21%

average and instantaneous rate of change
average is measured over some finite time interval. Instantaneous is not. It is the limit of the average rate, as the measured interval decreases to zero.

algerbra
Ethan donates 1/25 of which money? His earnings, the total earned, the total donated, or what?

math
you can convert the hours to minutes 14 X 60 = 840 then add the 3 minutes 840 +3 =- 843 then divide 843/3 = 281 then divide by 60 = 4 hours and 41 minutes

Math
Simplify the expression 14 to the minus 4 power

Math
Simplify the expression (-8x) times 3x squared

Math homework help
AG CE FH

Math
5+3√2

Calculus
the 3.02375 is correct, but you lost a factor of 10^-8 So, what you really have is .03 micrograms

Math - Bazinga!
you gotta be kidding. I suggest you pick out one or two of the types of questions that bother you, post your solutions, and we can check and/or critique them.

Algebra
.85^4

Calc Help Please Again!
the volume is just a stack of thin discs, of thickness dx, and radius y So, the volume is the integral of pi * y^2 dx = pi*(e^2x + 8e^x + 16) all pretty straightforward. C'mon back if you get stuck, and show where.

Algebra 1
first, draw the asymptotes. Then pick a few values of x near the vertical asymptotes, so you get a feel for how y behaves in that region. Then pick a few more values a little farther away, and draw the curve, keeping in mind that it will approach the horizontal asymptote on th...

trigonometry
tanθ=1/7 means sinθ=1/√50 cos 2θ = 1-2sin^2θ = 1-1/25 = 24/25 tanØ=1/3 means sinØ=1/√10 and cosØ=3/√10 sin2Ø = 2sinØcosØ = 3/5 so, cos2Ø = 4/5 sin4Ø = 2sin2Øcos2Ø = 24/25

algebra
not geometric. The ratio between terms changes. What you have is a modified Fibonacci sequence, where for n>=2, T(n+1) = 2*(T(n-1)+T(n))

trig
Assuming L is the right angle, the other two angles are complementary cos(N) = sin(90-N) = sin(M) the co- in cosine, cotangent, cosecant means "complementary" as in complementary angle.

chemistry
how many moles in 13g of CS2? The equation tells you that it takes 5 times that many moles of C. same for SO2. Figure the moles of C, then take 2/5 that many of SO2. Then go back to grams. Again, figure the moles, and recall that one mole of a gas occupies 22.4L at STP.

math(urgent)
well, of course they have two answers. They wanted to know the amount invested at each of two interest rates! So, what don't you understand? They gave you the equation. If P1 is invested at 12% (which is evident from the equation), then the rest of the money (30000-P1) was...

geometry
draw a diagram of a vertical cross-section of the cone, and mark off the altitude. You have a right triangle. The radius of the base is found from r/7.5 = cot(70)

business and finite calc
28000 is 0.666 std below the mean 35000 is 2.666 std above the mean. Now go to your Z table. Or, you can play around with this stuff at http://davidmlane.com/hyperstat/z_table.html

math
I assume you mean y=2^x and y=-2^x plot them just as you would any other functions. Mark off some points on the x-axis, and calculate the y values, then plot the points. x 2^x -2 1/4 -1 1/2 0 1 1 2 2 4 ... -2^x is just -(2^x), so it is below the x-axis, instead of above it. To...

physics
the distance s(t) = 12t - t^2 + c for some c. Since s(1) = -10, c=-21, and so s(t) = -21 + 12t - t^2 a = dv/dt = -6t so just plug in t=4 plug in t= 0 and 10 to find where the particle is at each time, then get the displacement by evaluating s(10)-s(0)

algebra - typo?
do you mean two numbers a and ar such that a+ar=28 and a*ar = 512? If so, then there's no real solution. Maybe there's something wrong with the way the problem is presented, eh?

Algebra
#1 There must be a typo here. Not factorable #2 (x^2-25)(x^2+4) now it should be easy #3 a little tinkering shows that you have (x+3)(x^2-6x+13) again, complex roots.

Math - Int Trig
#31 since f'(x) = -3x^2+2 the extrema are at x = ±√(2/3) f' > 0 for -√(2/3) x < √(2/3) so f is decreasing on that interval, and increasing elsewhere. #32 Since f(x) is odd, and the x^3 coefficient is -1, it rises to the left and drops to ...

Math - Algebra2
#1 surely you don't have to ask about this one -- the terms get ever larger #2 is simply a geometric series, with |r| < 1, so it converges.

Math
actually, you start with one bacterium. You need a function that doubles every time you add 1 to the time. You probably already are aware that this models exponential growth, so what such function doubles as needed? 2^x does the job. So, starting at time x=0, at time x hours l...

Calculus
clearly f(x) increases as x increases, since the slope is always positive.

Math problem or trick
sounds like it to me, since no one (probably) was wearing both.

pre algebra
so, what's the trouble? Just fill in the table x x^2 : x-x^2 0 0 : 0-0 = 0 1 1 : 1-1 = 0 2 4 : 2-4 = -2 and so on for whatever values you want.

pre algebra
Write a table for the following quadratic function. y = x - x squared

pre algebra
Write a quadratic function rule for the following table x -10 -5 0 5 10 y 80 5 -20 5 80

algebra
well, what is 3500 + 200 ln(1000) ??

Finite Math
P(even,~8) = P(2,4,6,10,12) = 1/36 + 3/36 + 5/36 + 3/36 + 1/36 = 13/36 P(8) = 5/36 P(odd) = 1-(13/36 + 5/36) = 1/2 So, Fred gets 8*13/36 + 1*5/36 - 2*1/2 = 73/36, or about $2

Calculus
what is the slope? (f(x1)-f(x2)) / (x1-x2) both are positive, so the slope is always positive.

math
what you mean is .25x = 20 x = 80

MAT 201
10 days is 1.33 std below the mean 21 days is 2.33 std above the mean just consult your Z table.

Science
most important factor: do not watch the clock!

Maths
x y 30 84 90 74 So, every extra 60 trees reduces the yield by 10kg, so y = -(10/60)x + c Since y(30)=84, (-1/6)(30)+c = 84 c=89 y = -x/6 + 89 The total yield is trees * avgyield, so x(-x/6+89) = -x^2/6 + 89x This is just a parabola, where the vertex is at x = 3*89 You can figu...

Physics
the police car is moving 20 km/hr faster, and must make up 1.6km. That will take 1.6km / 20km/hr = 1.6/20 hr No idea when that will be...

ALGEBRA
First step: sort the values from low to high. mean: add them up and divide by how many values there are median: the middle value -- same number less as greater. If there are an even number of values, take the average of the two center values. mode: The value(s) which occurs mo...

Math (functions)
just substitute in 1,2,3,4,... for n 3*1+5 = 8 3*2+5 = 11 3*3+5 = 14 3*4+5 = 17 Or, just start with 8 and keep adding 3 for the next terms.

Math (functions)
It is indeed. Since f(x) = 3x-2 for f(1.5), everywhere you see an x, replace it with 1.5 and then do the math.

chemistry pls help me asap
.96g of O2 is .03 moles So, since it takes 2 moles of Y to combine with 3 moles of O, and we have .03 moles of O2 (.06 moles of O), we have .04 moles of Y. So, the molar mass of Y is 2.08/.04 = 52

Algebra
4x+7 < 11 4x < 4 x < 1 1-x <= -2 -x <= -3 x >= 3 so, x<1 or x>=3 see at http://www.wolframalpha.com/input/?i=solve+4x%2B7%3C11+or+1-x%3C%3D-2

Math
3 mi * 15 min/mi = 45 min

math(urgent)
what you have done is calculate the first year's growth. Now you have to add the 2nd year: 1000(1+.08)^(2-1) = 1080.00 Then the third year: 1000 1166.40+1080.00+1000.00 = 3246.40 As you can see, for n years, you would have 1000(1+1.08+1.08^2 + ... + 1.08^(n-1)) = 1000(1.08...

Math
(1/4) / 3 = 1/12 think about it. If you cut a yard into 4 pieces, and then cut each of those (1/4 yard) into 3 pieces, there are now 12 equal pieces, of 1/12 yard each.

geometry
17ft * 17ft * 4 ft = 1156 ft^3 Now to convert that to $, 1156 ft^3 * (1yd/3ft)^3 * $50/yd^3 = $2140.74

Geometry
a little inspection (or drawing) will reveal that ABCD is a rectangle with width=3 and height=2 EFGH is a rectangle with width=6 and height=4 Since the width and height have both been scaled by 2, the two rectangles are similar.

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