Wednesday
November 26, 2014

Posts by steve


Total # Posts: 27,016

Calculus
f(x) increases means that f'(x) > 0 f'(x) = 2(x+3)(2x-11)/(4x-5)^2 So, just find the intervals where f'(x) is positive
November 22, 2014

AP Calc
hmmm. better see my solution to your previous posting. the distance should have (x-8)^2 + 4x, not (4x)^2, since 4x is already y^2!
November 22, 2014

AP Calc
one way to tell whether you did it right, is to show your work! Then we can see how you arrived at your result.
November 22, 2014

AP Calc - PS
Ignore the comment about the length of the normal line. The question did not actually ask for the distance, just the point on the curve. We just wanted to find the point where the normal to the curve passes through (8,0)
November 22, 2014

AP Calc
One way is to find the length of the line normal to the curve which passes through the point. The tangent at any point has slope 1/√x, so the normal line has slope -√x. The line through (8,0) and (x,2√x) has slope 2√x/(x-8), which we want to be -√...
November 22, 2014

algebra
#16 and #18 are correct though I must say the typesetting needs work The others, no idea. No diagrams or graphs here.
November 22, 2014

AP Calc
yep. nice feeling when it clicks, no?
November 22, 2014

AP Calc
the max or min area occurs where dA/dx = 0 dA/dx = 2(5x^4-6x^2+1) = 2(5x^2-1)(x^2-1) So, dA/dx = 0 at x = ±1/√5, ±1 Naturally, A=0 at x=1, so the obvious choice is x = 1/√5. Thus, the maximum possible area is 2/√5(1/5-1)^2 = 32/(25√5)
November 22, 2014

Physics
the tension is just the weight of the iron, minus the weight of the water displaced.
November 22, 2014

Chemistry
there are .03716*0.510 = 0.01895 moles of HCl Each mole of HCl neutralizes 1 mole of NaOH So, there were .01895 moles of NaOH in 0.025L of solution. Thus, the solution was 0.01895mol/0.025L = 0.758M
November 22, 2014

statistics
I found that the inversenorm is 83.5922, what do i do after this?
November 22, 2014

statistics
Ok but before we start we usually write downwhat the mean equals, standard deviation and X. Im still confused on which one would be the mean.
November 22, 2014

statistics
Hello i am doing assignment in my math 20-2 class. The question is: data collected of cars passing on the road revealed that the average speed was 90 km/h with a standard deviation of 5 km/h and the data which is normally distributed a policeman is assigned to set photo radar ...
November 22, 2014

maths
2score=40 2dozen=24 so, the cost will be 24/40 * 280
November 22, 2014

mechanics
stone 1: height is 40 + 20t - 9.8t^2 stone 2, 3 seconds later: 30(t-3) - 9.8t^2 they meet (or pass closely) when the heights are equal: 40 + 20t - 9.8t^2 = 30(t-3) - 9.8(t-3)^2 So, just solve that for t, and then plug that value into either equation.
November 22, 2014

Algebra 2
OK. But this is Algebra I, which you have presumably already passed. But, moving right along, 5x^2 - 16x + 6 = 0 The quadratic formula says that the roots of ax^2+bx+c are x = (-b±√(b^2-4ac)/2a So, for this problem, that means x = (16±√(16^2-4*5*6))/...
November 22, 2014

Algebra 2
Hmmm. By algebra 2 you should surely know how to solve quadratic equations... x^2+(4-2x)^2=10 x^2+16-16x+4x^2-10 = 0 5x^2 - 16x + 6 = 0 ...
November 22, 2014

Math
Review your text on partial fractions. You know that the sum will be (Ax+B)/(x^2+1) + C/(x-2) + D/(x-2)^2 If you put all that over a common denominator, you get (Ax+B)(x-2)^2 + C(x-2)(x^2+1) + D(x^2+1) ------------------------------------------------ (x^2+1)(x-2)^2 Expand ...
November 22, 2014

Math
I get (27x+14)/(x^2+1) - (27/25)/(x-2) + (8/5)/(x-2)^2
November 22, 2014

calc
I will assume you meant f'(0) = 3 in that case, f"(x) = 10 f'(x) = 10x+c 3 = 10*0+c -----> c = 3 f'(x) = 10x+3 f(x) = 5x^2+3x+c 1/3 = 5*0+3*0+c c = 1/3 f(x) = 5x^2 + 3x + 1/3 I figure you can now find f(1).
November 22, 2014

calc - typo
Sorry. If f'(x) is a constant, f"(x) = 0 Fix the typo and try again.
November 22, 2014

Fencing Applicatio
Clearly, P(f) = 500+20f There are lots of good graphing web sites. Or, heck, you can get out the old graph paper and a pencil!!! Imagine!!
November 22, 2014

Calc
You can set it up here to find out: http://mathworld.wolfram.com/RiemannSum.html
November 22, 2014

Math
clearly d=6 since T6 = T4+12 So, T1 = T4-18 = 19 T7 = T4+18 = 55
November 22, 2014

math
since the height:shadow ratio is the same for both, h/12 = 8/3
November 22, 2014

algebra
(3x)(4x^4) - (3x)(5x) 12x^5 - 15x^2 or, 3x^2(4x^3-5) Not sure what you mean by simplify
November 22, 2014

algebra
you have the formula. Just use your calculator, or any online calculator to find the values. For #1, just plug in t=5 For #2, just solve 3000 e^(0.07t) = 17700 e^(0.07t) = 5.9 0.07t = ln 5.9 ... For #3, just solve e^(0.07t) = 2
November 22, 2014

jm
study, study, study!
November 22, 2014

MATH
Cut a slice through the pyramid, perpendicular to one of the faces. You have a right triangle, with the base 18.6/2 and the hypotenuse of 14.8 Now just use the Pythagorean Theorem to find the height.
November 21, 2014

Math
First, you have to note that since log(z) is defined only for z>0, we must have x < -4/5 or x > 4/7 In that domain, there is an inverse. You made an error in your last line, which is where the trouble arises. It should be x = log (6y+5)/(7y-4) e^x = (6y+5)/(7y-4) e^x(...
November 21, 2014

Precalc
Since I have no diagram, I make the following assumptions. We can view the scene from high above, so the elevations of A and B make no difference. C is between A and B, but not on the line AB. The fire at F is on the opposite side of AB from C. So, we can use the law of ...
November 21, 2014

math help
so, if you divide f(x) by (x-4i) you get f(x) = (x-4i)(x^2+12x+32) = (x-4i)(x+4)(x+8)
November 21, 2014

Algebra 2
since we know y = 4-2x, use that: x^2+(4-2x)^2 = 10 5x^2 - 16x + 6 = 0 Now it's just the normal routine for solving a quadratic equation.
November 21, 2014

Math
well, it's 4 hours, and a full rotation is 12 hours. Tat help?
November 21, 2014

Physics
if we ignore air resistance, the bale's horizontal speed stays the same as the plane's. So, it remains directly below the plane till it hits the ground.
November 21, 2014

Algebra 2
you can easily check by substituting in those values to see whether they work in both equations. FYI, they do.
November 21, 2014

math
Actually, she can make 28 1/3 tacos. Since a taco uses .3 lbs, there is just .1 lb left over.
November 21, 2014

Math
m(x) = 4x, so m(f) = 4f = 12x^2 g(x) = 3x-1, do g(m) = 3m-1 = 36x^2-1 Using your nested notation, g(m(f(x)) = 3(m(f(x))-1 = 3(4(f(x))-1 = 3(4(3x^2))-1 =36x^2-1
November 21, 2014

mixture problems
If x is 25%, then the rest (10-x) is 50%. So, .25x + .50(10-x) = .40(10)
November 21, 2014

Math Help!!!
review your notes. There are whole numbers natural numbers integers rational numbers irrational numbers
November 21, 2014

math
9i/(-3+8i) = (9i)(-3-8i)/(3^2+8^2) = (72-27i)/73
November 21, 2014

Math
10000((1+.07*5)-(1+.06)^5) = 117.74
November 21, 2014

English PLEASE!!!
you picked a thermometer, which just measures. A thermostat affects things. So, the church influences society (by transforming the mores).
November 21, 2014

algebra
s = kv^2, so s/v^2 is constant. That means you want s where s/55^2 = 81/30^2
November 21, 2014

math
4/(5x-3)
November 21, 2014

Math Help!!!
#5,#8 no idea - no diagram #7 (-8,-10) (-8,10) is reflected through the origin. the others look good.
November 21, 2014

Math
amplitude is (125-99)/2 = 13 The center line is 125-13 = 112, not 122 2pi/k = 2*14, so k = pi/14 Since f(15) = 125, the max, that means that f(1) = 99, the minimum cosx has a max at x=0, so -cos(x-1) has a minimum at x=1. f(t) = 13 cos(pi/14 (x-1)) + 112 The graph at http://...
November 21, 2014

MAth Help
the vertical shift is +80 The curve oscillates about f=80 with an amplitude of 22. How did you arrive at 6?
November 21, 2014

Math
the vertex of y=a(x-h)^2+k is at (h,k)
November 21, 2014

algebra
you need x^2+y^2 = 100 So, which point works?
November 21, 2014

math
3:00 pm is 15 hours after midnight 6sin(pi/12 (15-11))+19 6sin(pi/12 * 4)+19 6sin(pi/3)+19 6*0.866+19 24.196 6+19=25 is the maximum possible temperature
November 21, 2014

algebra
x(2x+3) = 119
November 21, 2014

math
since the seat started at 60, it takes 1/2 turn to get back around to that height on the other side. That's 3.5 minutes
November 21, 2014

Math
√112 = ?
November 21, 2014

math
A B is an equation, not an expression C is too, and not even algebraic D is just a constant expression
November 21, 2014

math
Yes. In 1/4 turn, the wheel will be at the top.
November 21, 2014

math
any value between 64.8 and 65.4. For example, 65.0 64.800000000000000000000000000001 65.399999999999999999999999999999
November 21, 2014

plz help. math
Beckey! steven is mooching off your postings! Or, why not just use a single name, steven old buddy?
November 21, 2014

plz help. math
165 = 3*5*11 So, the table could seat 3,5,11,15,33,or 55 people The restriction on table size means that the only choices are 3,5,11,15
November 21, 2014

algerbra
If you mean √2, then the possibilities for a right triangle are 1 and 11, since 1^2 + √2^2 = 3 √2^2 + 3^2 = 11 If you meant 1/2, then the choices are √11/2 and √37/2 (1/2)^2 + 3^2 = √37/2 (1/2)^2 + (√11/2)^2 = 3
November 21, 2014

algerbra
try again. what is /2 ?
November 21, 2014

algerbra - incomplete
First, provide the length of the other side.
November 21, 2014

algebra
one way is to complete the square: x^2 + 5x + 3 = 0 x^2 + 5x = -3 x^2 + 5/x + (5/2)^2 = -3 + (5/2)^2 (x + 5/2)^2 = 13/4 x + 5/2 = ±√13/2 x = (-5±√13)/2 You get the same answer using the quadratic formula.
November 21, 2014

geometry
There are lots of sample constructions here: http://jwilson.coe.uga.edu/EMAT6680Fa08/Ruff/TriangleConstructions/TriangleConstructions.html
November 21, 2014

math
play around some at http://www.miniwebtool.com/hex-calculator/
November 21, 2014

MATH
Assuming hexadecimal, D5C
November 21, 2014

math
better check your text some more. With initial height h and initial velocity v, the height y at time t is y(t) = h + vt - 16t^2 So, you have y(t) = 20 + 5t - 16t^2 When working problems, don't forget what you know about parabolas -- their roots, vertex, etc.
November 21, 2014

college algebra
solve for t in 5300 * 1.077^t = 8000 * 1.056^t t = 20.9 years or, 21, since the interest is credited at year's end.
November 21, 2014

math (fractions)
mixed number
November 21, 2014

DON VASCO PATNA
you want 3/4 the concentration, so you must have 4/3 the volume.
November 21, 2014

algebra 2
just factor out the perfect squares: √25 = 5 √a^2 = a √b^5 = b^2 √b √(a^2/b^2) = a/b
November 21, 2014

Algebra II
you do have to remember to insert zeros for missing powers. Play around at http://www.mathportal.org/calculators/polynomials-solvers/synthetic-division-calculator.php
November 21, 2014

algebra
861bagels/3days = 287 bagels/day
November 20, 2014

math
father = 4y = brother+28 brother = father-28, so 4y-28
November 20, 2014

Algebra
31500(1+.068/365)^(365*30)
November 20, 2014

math
I'm sure you have a formula. For further reading, see wikipedia's article on Richter magnitude scale. It also has a table of sample values, so you can check your answer.
November 20, 2014

Math
2000(1+.05*18)
November 20, 2014

Math
Hmmm. Better make that Tn = n+3 if n is odd
November 20, 2014

Math
Looks to me like Tn = 2n+2 if n is odd Tn = 4*2^(n/2) if n is even
November 20, 2014

Physics
Vy = 7.4*1.7 = 12.58 m/s So, the final speed is √(8^2+12.58^2) = 14.91 m/s
November 20, 2014

math
Ah. missed the 5. So, yes, 5 3/2 = 13/2
November 20, 2014

math
12/8 = (3*4)/(2*4)= 3/2
November 20, 2014

MTH001
So, what are your truth tables?
November 20, 2014

math
If the original price is p, then the discounted price is 0.85p After the fee, the final price is 0.85p + 12 = 100 p = 103.53 That is not the greatest price; it is the only price which will cost exactly $100. It is the greatest price if she does not want to spend more than $100.
November 20, 2014

Math Help
#1. The figures are similar. Since 84/28=3, c/22 will also be 3. SO, c=66 #2. I believe you are correct. The 2nd triangle is 1/3 as big as the first. #3. No. Just double each coordinate.
November 20, 2014

math ?
no, but r=0, as a little synthetic division will show.
November 20, 2014

Math
s = 1/2 at^2 v = at, so t = v/a s = 1/2 a(v^2/a^2) = 1/2 v^2/a = 112^2/64 = 196 ft
November 20, 2014

Math
v(t) = 3/2 t^(1/2) s(t) = t^(3/2) + c 33 = 9^(3/2)+c, so c=6 s(t) = t^(3/2) + 6
November 20, 2014

Calculus
The slope at any point is y' = -7cosx The line through (0,0) and (x,-7sinx) has slope -7sinx/x. That means we need -7sinx/x = -7cosx x = tanx Solutions are x = 4.493409, 7.725252, 10.904122, ... The slopes of the lines are 1.521, -0.899, 0.639 See the first couple of lines...
November 20, 2014

math, please help
Looks to me like f(x) = (x-(-2))(x^2+4x+2)+0
November 20, 2014

Math Help
Looks good to me. Except "¢10 cents" is bogus notation. Try just 10¢
November 20, 2014

Math (IB Calc)
since cos(x) has it max at x=0, and you have a min there, A(x) = 50(1-cos(x)) now just plug in x = 2pi/3
November 20, 2014

Math Help
The scale factor of 2 means that (x,y) -> (2x,2y) So, you need to double the coordinates. Not sure what the heck you devised.
November 20, 2014

Math help!!!
First step: list the ordered pairs. (Mona,Kellie) ...
November 20, 2014

Math
You don't say whether these are courses from due North, or from the positive x-axis. I'll do the latter. the x- and y-components of the vectors are (450 cos65°, 450 sin65°) = (190.18,407.84) (35 cos20°, 35 sin20°) = (32.89, 11.97) Add them up to get (...
November 20, 2014

english
The current exchange rate is 1 yen = 0.0085 dollar So, a little less than 1 cent per yen. Or, a little more than 100 yen/$ 1/.0085 = 111.65
November 20, 2014

English
and you are correct.
November 20, 2014

Pre Calculus
P(0) = 160/(1+9) = 16 Just plug in t=6 for the population after 6 years. Note that as t->∞, e^-0.165t -> 0 So, the maximum possible population is 160 See http://www.wolframalpha.com/input/?i=160%2F+%281+%2B+9e^%28-0.165t%29%29+for+t+%3D+0..50
November 20, 2014

Pre Calculus
25*e^-5k = 18.4 So, k = ln(18.4/25)/-5 = 0.0613 So, now just solve for t in 25*e^-.0613t = 20.5
November 20, 2014

Pre Calculus
solve for m months in (1+.065/12)^m = 2
November 20, 2014

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