Monday
July 25, 2016

Posts by Steve

Total # Posts: 42,082

Maths
If the bottle holds b and a pen holds p, then we are told 2b/3 - 7p + 2p = x/4 5b/12 = 5p b = 12p
July 16, 2016

maths - eh?
fix your typos
July 16, 2016

CHECK MY ALGEBRA 2
Hmmm. I don't see any theoretical solution, but after 55 iterations g(x)=4, so that the next time g(x) = 4-2|2-4| = 4-2*2 = 0 g(0) = 4-2|2-0| = 4-2*2 = 0 and it stays zero Maybe roundoff error contributes to this result.
July 16, 2016

Math
well, the length of the base is 2 * 10 * sin15°
July 16, 2016

Math
95 = 5*19
July 16, 2016

Math linear equations
first step: expand to lose the parentheses: 10x-15-9x+21 = 5 Think you can take it from there?
July 15, 2016

Calculus1
Huh? How is this even possible? Anyway, just use the product rule to get a = 1/2 r^2 θ da/dt = 1/2 * 2rθ dr/dt + 1/2 r^2 dθ/dt So, now all you ave to do is find θ when a=20 and r=5 Then plug that in to solve for dθ/dt
July 15, 2016

maths
I'd just find the midpoint of AC or BD, since the diagonals bisect each other.
July 15, 2016

Precalc
google is your friend https://www.artofproblemsolving.com/wiki/index.php?title=2007_AMC_12B_Problems/Problem_19
July 15, 2016

precalc
In triangle ABC, the angles are A=45 C=60 so, B=75 These are inscribed angles, so if you draw radii from the center O to each vertex, you have AOB = 2*ACB = 120 BOC = 2*BAC = 90 AOC = 2*ABC = 150 Now you have three isosceles triangles. Each triangle with central angle θ ...
July 15, 2016

calc
scalar times vector = vector All the other operations produce vectors, so the result is a vector. vector dot vector produces a scalar, but that's not used here.
July 15, 2016

Business Math
so, do you have the formula? Can you plug in your numbers?
July 15, 2016

MATH
recall the distance formula: √(4^2 + 5^2)
July 15, 2016

Math
so, since x and y are integers, clearly x=y=0 is a solution If x>0, 2x-1 > x unless x=1, so x=y=1 is a solution For x>1, x/(2x-1) is a fraction. For x<0, x/(2x-1) is always a fraction, so (0,0) and (1,1) are the only integer solutions.
July 15, 2016

Maths
There are 7C5 ways to pick the consonants There are 5C3 ways to pick the vowels Each set of 8 letters can then be rearranged in 8! ways. This is assuming no duplicate letters.
July 15, 2016

Maths
well, there are 6 ways to answer 5 of the 1st 6 correctly (the same as the number of ways to get one of them wrong) That leaves 6 questions, of which 4 can be chosen in 6C4 = 15 ways. Each set of 4 can be answered in 2^4 ways.
July 15, 2016

Maths
no idea what the Cross Method is, but maybe you can fit these solutions into it. After giving away 1/4, there were 3/4 left, so x - x/4 - (1/3)(3x/4) = 120 x - x/4 - x/4 = 120 x/2 = 120 x = 240 Similarly, if Linda started out with $x, x - x/4 - x/3 - (1/5)(5x/12) = 18.50 x - x...
July 15, 2016

Maths
recall the sides ratios for a 30-60-90 right triangle: 1:√3:2
July 15, 2016

Johnson
distance of elevator from man: 22+2.0t distance of object: 6.5t + 4.9t^2 So, when are they equal?
July 15, 2016

Math
Looks like 11 girls in line
July 15, 2016

Math
The hexagon consists of six equilateral triangles, each with height (the apothem) 4√3 base 8 Now you can easily get the area. To get the base, review the properties of equilateral or 30-60-90 triangles.
July 15, 2016

maths
Draw a diagram. Review your basic trig functions. If the height of the pole is h, then h cot45° + h cot68° = 10
July 15, 2016

Algebra 2
if you mean linear, it has a term of the form ax where a is a constant, and it has no higher powers of x. More generally, it can be written in a variety of forms: ax+by+c=0 ax+by=c y=mx+b y-k = m(x-h) I'm sure your text covers it in some detail.
July 15, 2016

Math
as shown earlier, 3log_2(-x-6)
July 14, 2016

MATH
log_a(3) = log_b(27) log_a(3) = 3log_b(3) log_a(3)/log_b(3) = 3 log_b(a) = 3 b = a^3
July 14, 2016

Math
log_2(x) has asymptote at x=0, so log_2(x+6) has its asymptote at x=-6 But, its domain is x > -6. So, we want log_2(-x-6) at x = -8, we have log_2(8-6) = 1 So, we want y = 3log_2(-x-6)
July 14, 2016

Math(help please)
all we know is that 1/25 of the items are red pens. Assuming an integer number of items, that makes C the only reasonable choice.
July 14, 2016

Math
sorry - no pictures here. Surely you can draw a reasonable picture of lines a and b. Let a be the x-axis Then b is the line y=x (45°) Now, line c will be parallel to the y-axis. So, you now have a right triangle with two 45° angles.
July 14, 2016

MATH
or, to avoid introducing a new base, f^-1(x) = log1/3x = -log3x log and exponentiation are inverses, just like + and - * and / square root and square We just don't have any special symbols to denote the operation.
July 14, 2016

mathematics
These would be all the multiples of 24.
July 14, 2016

Math
u.v = 5*3*cosπ/3 = 15 * 1/2 = ?
July 14, 2016

pre cal
just plug in your numbers: cosθ = u•v ----------------------- |u| |u|
July 14, 2016

math
70^2 + 120^2 + 2*70*120 cosθ = 90^2 cosθ = -2/3 θ = 131.8° This makes sense, since if the two forces were separated by an acute angle, the resultant would be greater than either of them. Think of the parallelogram involved.
July 14, 2016

Math
not sure what that is, but it is the graph of log_3(x) reflected through the y-axis shifted right by 3 stretched vertically by a factor of 2 shifted down by 2 Note that log_3(-3x+9) = log_3(3) + log_3(3-x) = 1 + log_3(3-x) This cancels the scale factor on the x-axis by ...
July 14, 2016

Chemistry
well, 12g C + 32g O2 → 44g CO2 ?? If all 18g of C were used, there would be only 66g CO2. Am I missing something here?
July 14, 2016

algebra
it will take t hours, where 1.039^t = 2
July 14, 2016

Math
you want y(0) = 5, so log3(k^2)-1 = 5 log3(k^2) = 6 k^2 = 3^6 k = 27
July 14, 2016

Science
write the balanced equation convert grams to moles find the limiting reagent see how many moles of it will be used see how many moles of H2O will result convert back to grams
July 14, 2016

Maths
The factors of 6262 are 1x6262 2x3131 31x202 62x101 The first two are out, since there's no room for the blue border and red interior. So now, check the others and pick the one which allows for more red tiles. 29x200 60x99
July 14, 2016

physics
since the speed is uniform, its average is 30km/h
July 14, 2016

maths
rather than from 2:00 to 11:00, I read it as moving from, say 12:10 to 12:55, or 9/12 of an hour.
July 14, 2016

math
the number is between 3500 and 4500 So, now we start working with the info. The hundreds digit is even, so 363x 384x 400x 421x 442x If the digits add to 12, that means we can have only 3630 4008 4215 4422 So, what do you think?
July 14, 2016

math
as with all boxes, it is length * width * height = 21√5 * 12√3 * 25√3 = 18900√5
July 14, 2016

Math
That's what I get.
July 14, 2016

Math
that will be h(10)-h(9)
July 14, 2016

algebra
As we know, h(x) = a+bx-16x^2 a+b-16 = 148 4a+2b-64 = 272 solve that and you end up with h(x) = 4 + 160x - 16x^2 ...
July 14, 2016

Math
since 1/4 = 6/24, use that ratio for all the numbers. Then you have 1/6 : 1/8 : 1/4 1/6 - 1/8 = 1/24 Or, 4-3 = 1 Now scale that and you get 1/24
July 13, 2016

algebra
slope = distance/time
July 13, 2016

Math (PLEASE HELP!)
since cos(t) has a max at t=0, and we want the passenger to start at the bottom, a will be negative. r=13, so h(t) = -13cos(bt)+d h(0) = 1, so h(t) = -13cos(bt)+14 The period is 24, so h(t) = -13cos(π/12 t)+14
July 13, 2016

maths
Clearly you were having trouble, as you posted no work of your own.
July 13, 2016

maths
Clearly the floor is 0.1m thick. So, multiply the volume by the unit cost, and you get a cost of (7*3 + 6*2)(0.1)(65) = ?
July 13, 2016

math
since distance = speed * time 4(s-20) = 3(s+20) and we know what airspeed: it's its speed in the air. (note apostrophe)
July 13, 2016

maths114
The area of the minor segment is 1/2 r^2 (θ-sinθ) So, plug in your values and subtract that from the area of the circle, πr^2
July 13, 2016

Math
If they lost x games, then we have x + 3x+15 = 95
July 13, 2016

maths 114
area of circle minus area of minor segment.
July 13, 2016

math
(x-1)y" + 2y' = 0 If we expand about x=0, we assume y = ∑anx^n y' = ∑nanx^(n-1) y" = ∑n(n-1)nx^(n-2) Plug these into our DE and we have (x-1)∑n(n-1)nx^(n-2) + 2∑nanx^(n-1) = 0 ∑n(n-1)nx^(n-1) - ∑n(n-1)nx^(n-2) + 2&#...
July 13, 2016

Math
well, since 3 = 18/6, the cost is X/6
July 13, 2016

math
well 64πh = 384π
July 13, 2016

maths
6cis 5π/6 * 3cis 4π/5 = 6*3 cos(5π/6 + 4π/5) = 18 cis 49π/30
July 13, 2016

analytic geometry
since (8,0) divides the line into a proportion, (8-x)/(10-x) = (0-7)/(y-7) y = 14/(x-8) There are many possible lines. A few possibilities are x=9, y=14 x=10, y=7 x=15, y=2 x=22, y=1 x = -6, y = -1 x = 1, y = -2 x = 6, y = -7 x = 7, y = -14
July 13, 2016

math
t = 2-x, so y = 1+2(2-x) = 5-2x At t=0, we have (2,1)
July 13, 2016

Math
If x is the original number, x/24 = x-16 Comes out a fraction. If, on the other hand, you meant to say he got a quotient which was 16 less than the correct quotient, then we have x/24 = x/12 - 16 x = 384 I suspect you have garbled the question.
July 13, 2016

Maths - duh
Stupid me. I read the question as "two equal parts" and wondered what the fuss was about. Clearly the ratio would be 1:1 Nice catch, Reiny.
July 13, 2016

Maths
what do you mean by "their areas"?
July 13, 2016

math
it has to make up 130 miles in 3 hours. So, its speed is 65 + 130/3 mi/hr
July 13, 2016

pre-calculus
well, for 30° it is (1/2, √3/2) Now move that around 180°
July 13, 2016

computer sc.
no diagrams, but the steps are n=50 i=0 sum=0 get score i += 1 sum += score i<n? If so, repeat avg = sum/n
July 13, 2016

Pre Calculus
or, more directly, using deMoivre: 8cis10 * 5cis200 = 8*5 cis(10+200) ...
July 13, 2016

math
just plug in the numbers where F = 9/5 C + 32
July 13, 2016

math
speed = distance/time, so 1.4km/1.667hr = 0.84 km/hr or, using fractions, (7/5)km/(5/3)hr = 21/25 km/hr
July 13, 2016

Algebra
6/20 --------- = 2/5 3/4
July 12, 2016

Math
y = a(x+3)(x+1)(x-4) at x = -2, (x+3)(x+1)(x-4) = 18 so, y = 4/3 (x+3)(x+1)(x-4)
July 12, 2016

Pre-Cal
Draw your triangles in standard position. Then it is clear that sinx = -4/5 tanx = 4/3 cosy = -√77/9 tany = -2/√77 Now just plug the needed values into the identities you have
July 12, 2016

Pre-Cal (Help Please!!!!)
#1 cosθ (3tan^2θ - 1) = 0 so, cosθ = 0 or tanθ = ±1/√3 Those are standard familiar values, right? #2 tan3θ = -1 3θ = 3π/4 or 7π/4 + n*π/3
July 12, 2016

Math
Just factor as usual: 2x + 9√x - 5 = 0 (2√x-1)(√x+5) = 0 √x = 1/2 x = 1/5 √x = -5 no solution there
July 12, 2016

Algebra
just expand and equate coefficients 4x^2+20x+r = 4x^2+4sx+s^2 4s=20 s=5 r = s^2 = 25 r-s = 20
July 12, 2016

Physics
F = ma, so a = F/m = 18N/6kg = 3 m/s^2 v = at = 3*5 Now you try the other. Same ideas.
July 12, 2016

maths studying for pre cal test
draw angle A and side b. Now, if it were a right triangle, with b the hypotenuse, side a would be the altitude, of length 14 sin60° = 12.12 So, you see, a little side a of length 4 will not reach down the the base, AB. If C is the right angle, that means that tanA = 6/14, ...
July 12, 2016

Studying for math test
Read the question carefully. It said which of the following is not equivalent? Actually, both c & d are not
July 12, 2016

Studying for math test
take a look at the related questions below. In particular, http://www.jiskha.com/display.cgi?id=1468255540
July 12, 2016

12th grade chemistry
normalbold
July 12, 2016

12th grade chemistry
<pre> abc def ghi jkl </pre>
July 12, 2016

12th grade chemistry
<font size="4">size 4</font> <font size="2">size 2</font>
July 12, 2016

12th grade chemistry
abc<small>abc</small>
July 12, 2016

science
well, p = mv plug in your numbers and solve for v.
July 12, 2016

chemistry
note that each 2 moles of KOH produce 1 mole of Mg(OH)2. So, how many grams in 2 moles of magnesium hydroxide?
July 12, 2016

MATHS
42°
July 12, 2016

MATHS
3x+A=45 x = (45-A)/3 Is there something else you want to specify?
July 12, 2016

Math
or, differentiating y' directly, y" = 50y^3(-5xy^2+20xy+18)/(10xy+9)^3 y"(1,1) = 50(-5+20+18)/19^3 = 1650/6859 which agrees with Reiny's result above!!!
July 12, 2016

physics
How long does it take the bomb to fall 8000m? 4.9t^2 = 8000, so t=40 s In 40s, the bomb will travel 8000m. What a coinkidink! So, the angle is just 45°
July 12, 2016

math
just solve 3x + 1/2 x^2 = 8
July 12, 2016

pre cal
splashdown occurs when h=0 max height is at t = -b/2a = 115/9.8
July 12, 2016

agebra
well, if you know the mean and the std, µ-2σ <= x <= µ+2σ
July 12, 2016

math
dy/dx = xy dy = xy dx dy = 1*2 * 0.4 = 0.8
July 12, 2016

pre cal
recall that the vertex of a parabola is at t = -b/2a so evaluate h(t) there.
July 12, 2016

maths
Just change the numbers in Reiny's solution here: http://www.jiskha.com/display.cgi?id=1455402753
July 12, 2016

pre cal
well, the diagonal of the square is the diameter of the circle...
July 12, 2016

pre cal
The time it takes for the sound to come back is d/c The time it takes to fall a distance of d is found using h0 + v0 t - g/2 t^2 = d Solve that for t, and then you have t = 1/g (v0 + √(v0^2 - 2g(d-h0))) Now you know that 1/g (v0 + √(v0^2 - 2g(d-h0))) + d/c = t Now ...
July 11, 2016

Algebra/Calculus
note that (x+y)^2 = x^2+2xy+y^2 x^3 + y^3 = (x+y)(x^2-xy+y^2) Now just plug in what you know.
July 11, 2016

algebra 2
3x-15 = 0 when x=5 everything else is ok.
July 11, 2016

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