Sunday
January 25, 2015

Posts by steve


Total # Posts: 28,309

Math
the speed (distance/time) is constant, so that means 5/37 = 25/m None of the choices matches that exactly, but it is easy to see that (C) is the same equation.
January 12, 2015

Math
If you really want to use the index as you did, just type 2root or 3root. "square root" always means index of 2.
January 12, 2015

Math
in that case, yes. If there is no index, 2 is assumed. Online, its usually better to say sqrt for square root cbrt for cube root 4throot, 5throot, etc. x^(1/n) for the nth root. It's too easy to mistake the desired index for a multiplier.
January 12, 2015

Math
the two temperatures are equidistant from their average, (10.4+7.6)/2 = 9.0 So, you have |t-9.0| = 1.4
January 12, 2015

To: Anonymous and all others
Well done, student! These are model posts of homework problems. The problem is clearly written, possible answers are given (optional, of course), and the student's answer is noted, along with an indication of the solution method. If actual work had been shown, that would ...
January 12, 2015

math
1/12 + 1/x = 1/4 x = 6 so, 6 hours for the friend.
January 12, 2015

Math
well, since 0.7 = 7 * 0.1, add up seven times 1/10 of 0.7. That is, divide the 0.7 into ten equal pieces, and add up 7 of them. divide 1/4 into 5 equal pieces. Add up 4 of them.
January 12, 2015

algebra 2 help
3|x+4| = 8 |x+4| = 8/3 so, x is 8/3 away from -4, either + or - A is the solution to |x+4| = 6 or 3|x+4|=18 B is the answer to |x| = 2 C is the answer to |x+4| = 15 D is the answer to |x+18| = 4 If you have a typo, the answer may be (A) And if you can't even spell "...
January 12, 2015

chemistry
does HCl dissolve Al2O3? It probably reacts with it, instead. If that's what you meant, then figure how many moles of Al2O3 you have, then check the reaction to see how many HCl it takes to react with one Al2O3. Then you will need that many moles of HCl. Convert that back ...
January 12, 2015

Maths literacy, accounting, economics and business studies
It certainly looks like good preparation. Especially the Accounting course ...
January 12, 2015

physics
Since there are 86400 seconds and 40030 km in the earth's circumference, the plane must travel 40030/86400 km. Assuming east-west travel at the equator. I assume that the question is ignoring the truly minuscule relativistic effects of such a slow speed. Also, what are the...
January 12, 2015

Please check my Calculus
all look good to me. No reason to be unsure on #2. Just the chain rule. If u = 3x, y=sec u y' = secu tanu u'
January 12, 2015

Geometry
min diam = 39.5 max diam = 40.5 area = pi d62, so plug in the values for d. Use the two values for d to get the dimensions of the box. The box's sides must equal the ball's diameter, right?
January 12, 2015

Geometry
they are the sides of the drum. Their area is circumference * height.
January 12, 2015

Please check my Calculus
#1 there are 4 points of inflection, so (E) #2 f = x^2-4x+7 f has a min at x=2, so C or D f(0) -> 7 f(3) = 4 So, (d) #3 is correct On stuff like this, it is always helpful to verify your calculations with a graphing utility, of which there are many online.
January 12, 2015

Please check my Calculus
#1,2 are ok #3: f' = 16/x^2 16/x^2 = (8-2)/6 = 1 x^2=16 x=4 in [2,8] So, (A) is correct
January 12, 2015

Please check my Caclulus
#1 ok #2 h' = (f'g-fg')/g^2 = (6*1-0*1/3)/1 = 6 So, B is correct #3 f' = -(x^2+2)/(x^2+x-2)^2 f' < 0 for all x So, (D) is correct
January 12, 2015

math
since you got -1 for your final answer, did you try it to see whether it works? How about y=0? (0+1)(0/(1-0)) = 0, not -1 assuming you meant (y+1)(y/(1-y^2)) (y+1)(y) / (1+y)(1-y) y/(1-y)
January 11, 2015

math
√(4/3) - √(3/4) 2/√3 - √3/2 2√3/3 - √3/2 4√3/6 - 3√3/6 √3/6 (C)
January 11, 2015

college pre-calculus
1 - 1/x = 2 - 2/x 1 - 1/x = 2(1 - 1/x) so, 1 - 1/x = 0 x = 1 so, 3 - 3/x = 3 - 3 = 0
January 11, 2015

Math
(a) You need 3 dimensions for volume. What you have is the area of one of the sides of the box. You need (100-2x)(100-2x)x = x(100-2x)^2 (b) You need the area of the base, plus the area of the 4 sides: (100-2x)^2 + 4x(100-2x) = (100-2x)(100+2x) (c) Now that you have the two ...
January 11, 2015

physics
If the gun were fixed in place, all the momentum would transfer to the bullet, which would then have momentum p = mv = .0551kg * 320m/s But, the gun will recoil, and we have to divide that momentum into two parts. So, if the gun has velocity v, the actual ground speed of the ...
January 11, 2015

Calculus
Since f(x) is not defined for x = ±2, any interval which includes either of those values will not satisfy the theorem. So, A,B,D are all out The only possible choice is C, which is ok, because f(-3/2) = f(3/2)
January 11, 2015

Calculus
Since we know nothing about f'(-4) or f"(-4), we can say nothing about the properties of f there. However, if the change in sign is inadvertent, and all the data are about x=4, since f"(4)=0, x=4 is an inflection point.
January 11, 2015

8th Grade Geometry
since the triangles are similar, we know that the angles A=X, B=Y, C=Z So, 2x+5y = 50 Y = 102-x C = 5x+y Also, the angles have to add up to 180. So, 50+(102-x)+C = 180 (2x+5y)+Y+(5x+y) = 180 Putting all that together, you can get 50+102-x+5x+y = 180 2x+5y+102-x+5x+y = 180 or, ...
January 11, 2015

Calculus
since f'(-2)=0 and f"(-2)>0, (-2,5) is a minimum. (f is concave up there)
January 11, 2015

Area and Perimeter Word Problems
area = 10x, where 2(x+10) = 50
January 11, 2015

Area and Perimeter Word Problems
what is 4700/94 ?
January 11, 2015

Calculus
well, you just find where f'=0 and f"≠0 for extrema f"=0 for inflection points f' = (3x-1)(x-3) so, f'=0 at x = 3, 1/3 f"(1/3) < 0, so f(1/3) is a maximum f"(3) > 0, so f(3) is a minimum f"=0 at x = 5/3, so there's an ...
January 11, 2015

Calculus
Check out the graph, and scroll down to information on the extrema at http://www.wolframalpha.com/input/?i=%28x%2B1%29%28x-3%29^2 I think you are doing things right.
January 11, 2015

Area and Perimeter Word Problems
well, 15*15 = 225, so ...
January 11, 2015

maths
the cross-section area of the water is πd^2/8 = 49π/8 So, the water flowing through is (49π/8 cm^2)(2m/s)(10min) = 2309 liters
January 11, 2015

Calculus
Or, you can plot multiple curves to compare them: http://www.wolframalpha.com/input/?i=plot+y+%3D+%3Dx^2%2F%28x^2%2B5%29+%2C+y%3Dx^2%2F%28x^2%2B20%29
January 11, 2015

Calculus
I believe the answer is (A), given the interval [-3,-½]
January 11, 2015

Calculus
or, you can think of it as 5x^2-(2xy)+7y^2=0 and since (2xy)' = 2y+2xy', that gives 10x-(2y+2xy')+14yy' and go from there.
January 11, 2015

Math
(x+2)^2 = x^2+4x+4 So, the first is clearly not the same (x-2)(x+1) / (3x+1)/(x+1) = (x-2)/(3x+1) So, except for the missing division symbol, the 2nd is ok.
January 10, 2015

Maths
You can set up the vertices PQRS as points on the x,y,z axes such that P = (0,0,c) Q = (0,b,0) R = (0,0,0) S = (a,0,0) Then the midpoints are: PS: (a/2,0,c/2) QR: (0,b/2,0) PR: (0,0,c/2) QS: (a/2,b/2,0) You can easily show that the lengths of those segments are equal. There&#...
January 10, 2015

PreCalc
In general, there is no way to solve anything of 5th degree or higher. So, unless you can pick out some rational roots or easy quadratic factors, you are left with graphical or numeric methods.
January 10, 2015

Integrals
Assuming you meant 3x+5y < 15, just plug in allowable integral values for y: y 1: 3x+5 < 15 2: 3x+10 < 15 I think you can solve those, right?
January 10, 2015

maths
I get 8+7
January 10, 2015

maths
At a rate of 5 m/min, after 36 minutes he has gone 180m. On the 37th minute he swims 20m and is done. No need to let go and float backwards again.
January 10, 2015

maths
I have no idea what a sequence and series pattern involves, but surely you do. Try fitting Reiny's solution into your framework.
January 10, 2015

maths
37 minutes see previous solution for the explanation.
January 10, 2015

Math
What, still no work of your own to start with? Try factoring the quadratics, and see which factors cancel. And lose all those stupid parentheses around each term. Use one set of parens around the whole numerator or denominator.
January 10, 2015

math
No, because 4/9 = 16/36
January 10, 2015

Math
I don't see any way to simplify either one, except maybe to lose all the parentheses in the first one.
January 10, 2015

english n engg.level to find d error related
I hope it's not in English...
January 10, 2015

Algebra 1a
the lines meet where the x- and y-values are the same (9x+27)/3 = (72-8x/9) x = -153/19 so, y = 288/19
January 10, 2015

Math
since 12 = (3/2)*8
January 10, 2015

Math
helps to read: since 12 = (3/2)*8
January 10, 2015

math
just set x=0 and see what y is. That is the y-intercept -- where the graph crosses the y-axis (where x=0). Better review the examples and graphs in your text.
January 9, 2015

algebra
factor out the (x-y): (x-y)(4(x-y)^2-1) Now you have a difference of squares: (x-y)(2(x-y)+1)(2(x-y)-1) ...
January 9, 2015

math
because 15 minutes is 1/4 = .25 hour. So, 1 hr 15 min = 1.25 hours distance = time * speed, as calculated.
January 9, 2015

math
he ran 1.25 * 12 km Now convert that to meters.
January 9, 2015

Intro to computers
there are 4 memory sticks, each with 1GB of storage.
January 9, 2015

Math
well, what is a when t=0?
January 9, 2015

Math 6 help
By the way, the scale is 1:9, not 1:9cm Or, you could say it is 1cm:9cm It could have any units, for example, 1cm:100m 2mm:3km etc. If there are no units, you can make them both anything you want, as long as they are the same. If one unit is given, the other must also be ...
January 9, 2015

math
She's also good with spelling. Just sayin' ...
January 9, 2015

algebra 2
Apparently you want to simplify the expressions. I'll do #19. y^3/y^2 = y z^5/z^3 = z^2 So, you are left with -yz^2 Try the others. What do you get? If in doubt, show your work.
January 9, 2015

Algebra 1
Surely by this point you know how to graph a straight line. Graph both lines, and you will see that they intersect at (5,75). Just put a nice dot where the lines intersect. You might want to have a larger scale on the y-axis than on the x-axis. Just sayin'.
January 9, 2015

math
Check the differences: 9,16,25 Those are perfect squares. The next square is 36, so the next term in the sequence is probably 57+36 = 93
January 9, 2015

Math
So, can you not just plug in some values and check the results? I'll show you my work if you'll show me yours... Note: Usually it's easiest to use -1,0,1 for checking stuff.
January 9, 2015

CAL
Come on. There's no way to have two relative maxima without either a minimum or an inflection point in between them. y' = 15(x^4-5x^2+1) y" = 30x(2x^2-5) y" =0 when x = ±√(5/2) So, f is concave down in (-∞,-√(5/2)) up in (-√(5/2...
January 9, 2015

Deductive reasoning help
From your question, I deduce that you haven't studied hard enough. This seems to be a pattern among students.
January 9, 2015

Calculus
How about just writing down a few terms? 5^1 - 5^0 5^2 - 5^1 ... 5^100 - 5^99 --------------- 5^100 - 5^0 If you want to do it the hard way, you could note that ∑(a-b) = ∑a - ∑b
January 9, 2015

math
since circumference is just a constant multiple of radius, the circumferences are in the same ratio as the radii.
January 9, 2015

Multiplying Polynomials
The order of distribution does not matter, since the associative property guarantees that the order of grouping does not matter, and the commutative property guarantees that the order of multiplication does not matter. You can drag it out by brute force: (t-1)(t+1)(t^2+1) t(t+...
January 9, 2015

Math
well, did you check 24 to see whether it satisfies the conditions?
January 9, 2015

math(5th grade)
Since there are 1440 minutes in a day, that would be 1000000/(25*1440)
January 9, 2015

MATH
Try plugging x=0. Does 7(-2) = 0+14? Do the same for #2. Does -10(-2) = 10-10(-1)?
January 8, 2015

trigonometry
well, you know that sinθ = 3/10
January 8, 2015

Algebra 1
The amount of oil should be twice the amount of lemon juice. y = 2x How much of each ingredient is needed to make 45 ounces of floor wax? x+y = 45
January 8, 2015

Algebra
http://www.wolframalpha.com/input/?i=solve+2x+-+y+%3D+1%2C+x+%2B+2y+%3D+3+
January 8, 2015

6th grade math
I parsed the words as 7 times as long as (x minutes more than a platypus)
January 8, 2015

6th grade math
7(x+10) = 112
January 8, 2015

Algebra 1
12 x^-2 y^4 = 12y^4/x^2 -3xy^-7 = -3x/y^7
January 8, 2015

Algebra 1
for any nonzero number, x^0 = 1 by the way, your brackets are not balanced. Try using [ ] instead of those block graphics symbols. They're right there on your keyboard.
January 8, 2015

MATH
If there are x married men (or women) y single men z single women, we want 2x/(2x+y+z) (x+z)/2 = z (x+y)/6 = y x = z x = 5y so, z = 5y 2x/(2x+y+z) = 2*5y/(2*5y+y+5y) = 10/16 = 62.5% Check: If 1 single man 5 single women 5 married couples there were 16 people in the room. 10 ...
January 8, 2015

Ap calc
You should also know that y = tanh(x) y' = sech^2(x) = [2/(e^x+e^-x)]^2
January 8, 2015

Advanced Algebra
Is the ball punted straight up? If so, then h = 1+22t-4.9t^2 So, just solve for t when h<=5. If the ball was kicked at an angle, things get a bit harder, as the equation is then h = 1 + 22sinθ t - 4.9t^2
January 8, 2015

Math
since the fill rate is volume/time, and is constant, then just solve (40^2 * 5)/50 = (36^2 * 4)/x
January 8, 2015

math
check your other post for the answer.
January 8, 2015

MATH
15-.75x = 13-.50x Now just find x 15 - 3/4 x = 13 - 1/2 x 60-3x = 52-2x 8 = x After 8 games, Julia has 15-8*.75 = 15-6 = $9.00 Kevin has 13-8*.50 = 13-4 = $9.00
January 8, 2015

math
k = 2a k-7 + a-7 = 31 so, 2a-7 + a-7 = 31 3a-14 = 31 3a = 45 a = 15 So, Amy is 15 and Ke is 30 7 years ago, 8+23 = 31
January 8, 2015

algebra
google is your friend. So is any used book store. This site is not for long instruction, but for homework help.
January 8, 2015

Algebra 1a
First off, there are no "these two points." Second, the solution to the system of inequalities is a whole region of the plane, not just a point. If we are dealing with equations, then the point where the lines meet is (-126/11, 21/11) The shaded region in the plot ...
January 8, 2015

Geometry
since 24/16 = 3/2, the perimeter will be 3/2 as big. All the sides are 3/2 as big.
January 8, 2015

Math
S = 9/(1-r) If r>=0, you can see that 9/1=9 would be the smallest possible sum, if r=0. That is, if the sequence is 9 0 0 0 0 0 ...... Any other value for r will produce nonzero terms, and therefore a larger sum. You can investigate what happens when r < 0.
January 8, 2015

Math
These are just your basic trig functions. Review them and the first three are trivial. I'll do #4. sin^2x / 1+cosx (1-cos^2x)/(1+cosx) (1-cosx)(1+cosx)/(1+cosx) 1-cosx If indeed your teacher assigned these problems with no prior introduction to the trig functions, then don...
January 8, 2015

math
x+19 >= 8.2
January 8, 2015

Useless Science Question
the question is "what is missing?" It doesn't want an answer to what it should be.
January 8, 2015

Useless Science Question
the units km/hr, m/s, cm/ms ?what?
January 8, 2015

Pre-Calc/Trig
eq #1 says that 7y^2=5x^2-20x+3, so plug that into eq #2 and you have 5x^2+3(5x^2-20x+3) = 209 20x^2-60x-200 = 0 x^2-3x-10 = 0 (x-5)(x+2) = 0 And I think you can take it from there, no?
January 8, 2015

science
I'd get the answer by looking it up somewhere. Unless you have some data about amounts and times, there's no way to figure it out yourself. Can you see what a useless question you have posted? Sheesh! And, I think you have missed your deadline...
January 8, 2015

Math
x^2-3x-4 = (x-4)(x+1) So, you have x/[(x-4)(x+1)] - 4/(x+1) (x - 4(x-4))/[(x-4)(x+1)] (16-3x)/[(x-4)(x+1)] As usual, you cannot divide by zero, so any values of x that make a denominator zero are excluded. Now show us what you got on the others you posted. As it says, show ...
January 8, 2015

Math
what the heck are tries toom points ? If this is the old trisection problem, then you know that AQ = 2 PQ, so 7x+6 = 2(3x+5) 7x+6 = 6x+10 x = 4 PQ = 17 Now, AB = 3 PQ = 51
January 8, 2015

math
-1 < 2x/3 + 1 <= 4 Add 1 to get 0 < 2x/3 <= 5 times 3/5 to get 0 < x <= 3 Looks like x is any of 1,2,3
January 8, 2015

calculus - ps
Sorry - I forgot to include the factor of a on the right side. It will just multiply the final answer, since it's a constant.
January 8, 2015

calculus
(x-y)(x^2+y^2) = 2axy In polar coordinates, that is r(cosθ-sinθ)(r^2) = 2ar^2 sinθ cosθ r(cosθ-sinθ) = asin2θ r = asin2θ/(cosθ-sinθ) The loop is the area enclosed as θ goes from π/2 to π, so the area is a = &#...
January 8, 2015

MNHS_HELP
63^3+63^2+63+1 = (63^4-1)/(63-1) = 63^4-1 So, your number is 63^4-1+1 = 63^4 = 3^8 * 7^4 So, the prime factors are 3 and 7 I'll leave it to you to determine how many factors there are in all
January 8, 2015

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

Members