Thursday

July 28, 2016
Total # Posts: 42,143

**Physics**

so, how long does it take to fall 0.75 meters? 4.9t^2 = 0.75 Using that time value, the constant horizontal speed is 2.0m/ts = 2.0/t m/s
*July 19, 2016*

**Math**

see related questions below. In particular, http://www.jiskha.com/display.cgi?id=1468483941
*July 19, 2016*

**calculus**

so, if the divisions are x meters long, we have 4*3 + 6x <= 100 6x <= 88 x <= 44/3 so, 8 <= x <= 44/3
*July 19, 2016*

**math**

The curved part (and maybe the base) is just half the surface area of the cone, for which I'm sure you have the formula. The interior which is exposed is just a triangle. Its area is also easy to find.
*July 19, 2016*

**Math**

2500(1+r/4)^(4*10) = 6000 (1+r/4)^40 = 2.4 1+r/4 = 1.022128 r/4 = 0.022128 r = 0.0885 = 8.85%
*July 19, 2016*

**Fpb science**

mumble mumble
*July 18, 2016*

**Busn math**

(3/35) / (9/7) = 3/35 * 7/9 = 3*7 / 35*9 = 3*7 / 5*7*3*3 = 1 / 5*3 = 1/15 or, you could do it (3/35) / (45/35) = 3/45 = 1/15
*July 18, 2016*

**Math (PLEASE HELP!)**

just in case you are having trouble solving exponential equations, eliminate k and you have 2 - 2^(-1-h) = -1 - 2^(-3-h) 3 = 2^(-1-h) - 2^(-3-h) 3 = 2^-h/2 - 2^-h/8 3 = 2^-h (1/2 - 1/8) 3 = 2^-h * 3/8 8 = 2^-h h = -3 Then k = -2, and g(x) = 2^(x+3)-2 See the graph at http://...
*July 18, 2016*

**Math (PLEASE HELP!)**

2^(-1-h)+k = 2 2^(-3-h)+k = -1 solve for h and k Of course many other values for b could have been chosen, but since only two data points were given, something had to be assumed.
*July 18, 2016*

**math**

20 + .15x = 35 + .10x
*July 18, 2016*

**Calculus rate of change**

A and B are ok. As for C, just showing that f" is a quadratic does not mean that it has two roots. However, if you went ahead and found that it must have two roots because the discriminant is positive, then ok. f is concave up (down) if f" is positive (negative), so ...
*July 18, 2016*

**Calculus @Reiny**

huh? height is twice the diameter, not half h = 4r Make that change, Nicole, and redo the steps.
*July 18, 2016*

**physics**

50mi/hr = 22.35m/s 22.35m/s / 4.5m/s^2 = 4.97s Now just plug in for distance: s = vt - 1/2 at^2
*July 18, 2016*

**physics **

the driver of the truck going 50 mph applies the brakes giving the truck a deceleration of 4.5 m/s^2 how long will it take the truck to come to a complete stop what distance will it cover
*July 18, 2016*

**physics**

a sports car can accelerate from 0 to 60 mph in 3.2s what is the acceleration of the car in m/s^2 what distance would it travel at this time
*July 18, 2016*

**Mathematics**

If the base has side length s, the total area is a square and four triangles with height 12 (the slant height): s^2 + 4 * (1/2)(12)s = s^2 + 24s Now just solve for s and recall that the volume is 1/3 Bh = 1/2 s^2h where h^2 = 12^2 - (s/2)^2
*July 18, 2016*

**Mathematics**

the area is a circular base, a curved side, and a hemisphere: πr^2 + 2πrh + 2/3 πr^3 Now just plug in your numbers.
*July 18, 2016*

**Physics**

Luchia's formula will enable you to calculate the distance of each portion of the trip. Then you just need to remember that avg_speed = total_distance/total_time
*July 18, 2016*

**Calculus**

been answered. Check previous posts.
*July 18, 2016*

**Physics**

120πm/2min = 60π m/min
*July 18, 2016*

**physics**

just use the formula KE = 1/2 mv^2 Now plug in your numbers
*July 18, 2016*

**trigonomentry**

draw a diagram review your basic trig functions now it is clear that you can find the height h using h cot 18°40' - h cot 26°22' = 50
*July 18, 2016*

**Mathematics**

f+2 = 6(s+2) f-3 = 5(s+2) either solve simultaneously, or note that (f+2)/6 = (f-3)/5 Solve for f, and then get s. Kind of a sloppy problem, using s+2 twice.
*July 18, 2016*

**Mathematics**

That is equal to (-2b^4y - b^2y^2 + y^2 + y^4 - 2)/(2y) I suspect you mean 1/(4(y+b))+1/(4(y-b))+y/(2(y^2-b^2))-y^3/(y^4-b^4) = (b^2y)/(y^4-b^4) parentheses can make a huge difference. Use them.
*July 18, 2016*

**physics**

at = .36 1/2 at^2 = 0.8 a = 0.081 Now you know that F = ma, so you can find F.
*July 18, 2016*

**physics**

distance = 3.5 * 2πr displacement = r at all times. After 3.5 revolutions, it is at the opposite end of the diameter where it started.
*July 18, 2016*

**Math**

look at the total wins and total games (12+10)/(25+10)
*July 18, 2016*

**MATH - @Writeacher**

I guess we'll just keep seeing the question until (a) an answer appears that he likes (b) the assignment is due (c) he posts his own solution
*July 18, 2016*

**MATH**

Seems like he'll get 1/4 of them right, and 3/4 of them wrong. So, I'd expect a score of 90*(1/4)*4 + 90*(3/4)(-1/4)
*July 18, 2016*

**science**

clearly false, since some acids are corrosive Maybe you meant "not all acids are corrosive" so, what ideas have you on that? what exactly do you mean by corrosive? Is lemon juice corrosive? Vitamin C? Boric acid?
*July 18, 2016*

**calculus**

cmon, guy - these are all basically the same. Figure the boundary, decide whether to use shells or discs, and add 'em up. For this one, either will work quite well. cylinders of thickness dx (or dy) have a volume of 2πrh dx discs have a volume of πr^2 dx the ...
*July 18, 2016*

**Word problems using equations**

so, the area of the park is 4/5 the total area including the path. If the path has width w, we have 30*24 = 4/5 (30+2w)(24+2w) or, you can say that the area of the path (the whole thing minus the park) is 1/4 the area of the park alone: (30+2w)(24+2w) - 30*24 = 1/4(30*24) ...
*July 17, 2016*

**Math**

consider the amount of antifreeze after adding x liters of pure antifreeze: .20*18 + 1.00*x = .40(18+x)
*July 17, 2016*

**Math**

20.00 + 0.64*100
*July 17, 2016*

**Math**

use the law of cosines. The distance z is found using z^2 = 3^2+4^2 - 2*3*4*cos(135) or, you can figure the x- and y-displacements, then use the distance formula as usual. 3N = (0,3) 4NE = (2.828,2.828) ----------------------- result: (2.828,5.828)
*July 17, 2016*

**math**

x = y^2(2-y) So the region in the 1st quadrant is a hump from (0,0) to (0,2) To revolve that around the x-axis it is best to use shells of radius y, thickness dy and height x. So, the total volume is ∫[0,2] 2πy(2y^2-y^3) dy = 16π/5
*July 17, 2016*

**Calculus**

Easy way: Consider the water to be concentrated at its center of gravity. How much work to lift that mass 4+3 feet? pi*5^2*8*62.5 lb * 7ft = 274889 ft-lb Calculus way: consider a thin slice of water of thickness dy. Its weight is pi * 5^2 * dy * 62.5 = 4908.734 dy lb Now lift ...
*July 17, 2016*

**Algebra 2**

If I read it right, you have (a+3)^2/a - (3/5)/(a^2-9) That is the same as (a+3)^2/a - 3/(5(a^2-9)) place all over a common denominator of 5a(a^2-9). Then you have 5(a+3)^2(a^2-9) - 3a --------------------------- 5a(a^2-9) (5a^4+30a^3-273a-405) / (5a(a^2-9)) which is not ...
*July 17, 2016*

**pre cal**

I think you are looking for (5,24). An interesting way to pose the problem.
*July 17, 2016*

**pre cal**

shrink horizontally by a factor of 8 stretch vertically by a factor of 8 If you think on it a bit, you should see why. Try using some online grapher to experiment.
*July 17, 2016*

**pre cal**

well, f(40) = 3 8f(8x) = 8f(320) Unfortunately, know f(40) tells us nothing about f(320). I think you have left out something.
*July 17, 2016*

**trigonometry**

just draw the triangle. The sides are 1,2,√5 Now just read off the trig ratios.
*July 17, 2016*

**Chemistry**

First, set up the balanced equation. .025L of .25M HCl has .00625 moles HCl. Now just see how many moles of CO2 are produce for each mole of HCl. Convert the result to grams.
*July 17, 2016*

**Math**

Hmmm. Hard to see. The length is 36 and the width is 20. If the height of the box is x, then the base would be 18-x. With the other edge width=20, I don't see how the base can be square.
*July 17, 2016*

**pre cal**

g(x) = x^2 extra credit: shifted by how much in each direction?
*July 17, 2016*

**Microsoft Excel**

you could always try the different forms and see which works. Just sayin' ...
*July 17, 2016*

**science**

well, K = 10^(212/400) = 10^0.53 = 3.388 you can use that
*July 17, 2016*

**MAth**

the amplitude is clearly 7.2, so start with y = 7.2 cos(kt) The period is 2*6=12 hours, so k = 2π/12 = π/6 y = 7.2 sin(π/6 t) Now we are stuck. The tide starts at 2m, but is that on the way down, or the way up? And how can that be the trough? The trough is at -7...
*July 17, 2016*

**College Algebra**

first of all, it's just an expression, not an equation (no = sign) Since loga + logb = log(a*b) just a x^a * a^b = x^(a+b) log x^n = log(x*x*x*x...)= n*logx assuming logs base 5, but the base does not matter if all the logs are to the same base; the rules apply regardless ...
*July 17, 2016*

**@@**

Still, just posting the answer does allow the student to check his results. After all, that's what they really are after, right?
*July 17, 2016*

**mathematics**

well, just crank it out: a1=1 a3 = 3a2+2 ... Of course, you do have a problem, since a2 is not defined. Because of a typo.
*July 17, 2016*

**math**

check all the powers. Th highest power present for each variable will be in the GCF. (common factor, right?) So, you have 90x^6y^6 18x^4y^4 27x^2y^2 The biggest thing common to all those terms is 9x^2y^2
*July 17, 2016*

**Calculus**

that's PI, not pie!! and I have no idea what g.r means. g(r) = 4/3 pi r^3 = 4/3 pi (3t)^3 If you want, you can expand that out. This is just Algebra I, right?
*July 16, 2016*

**Math**

I assume the prism has a triangular base and a height of 23. A right triangle with legs of length 12 has sides 12,12,12√2 so, where does the 9 come in? Do you mean a right triangle with legs of length 9 and 12, and thus a hypotenuse of 15? If so, then add up the areas of...
*July 16, 2016*

**maths**

that depends. Are the matrices in any way related to the coefficients in the planes' equations?
*July 16, 2016*

**Algebra 2**

I would say yes. Have you read your TI-84 manual? Have you tried google? I did, and got https://www.google.com/search?q=TI-84+calculator+recursive+functions&ie=utf-8&oe=utf-8
*July 16, 2016*

**Maths**

If there are x chocolates, then we see that x(1 - 1/5 - 1/6) = 38 Now just solve for x
*July 16, 2016*

**math**

since there is an even number of values, the median is the average of the two center values: 9, not 11
*July 16, 2016*

**math**

well, the numbers are 5,7,11,13 I'm sure you can figure the mean and median.
*July 16, 2016*

**maths**

Well, clearly there is no unique solution involving z. Apparently x=3 and y=0 So, any point of the form (3,0,z) will satisfy the equations.
*July 16, 2016*

**math**

The machine makes 12000 pieces per day. So, to pay for itself in x days, you need 12000/50*3.00*x = 9000
*July 16, 2016*

**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*