Wednesday

July 27, 2016
Total # Posts: 42,116

**Physics**

time to accelerate 10m/s / 4m/s^2 = 2.5s deceleration takes twice as long, since the rate is half as great. Now figure the distance using the good old formula s = vot + 1/2 at^2 for each part of the trip.
*July 23, 2016*

**Math**

good work, but if you are going to include the units in your expressions, it is important to be careful with them: 48hours x 5seconds=240 hour-seconds what you need to do is make sure that the units cancel properly. 48hr x 5s/hr = 240s
*July 23, 2016*

**Linear equations in 1 variable**

Add up their value: 5x + 2(3x) = 77 Now find x and thus 3x.
*July 23, 2016*

**Maths**

2(x+y) = 62 xy = 198 x+y=31 y = 31-x x(31-x) = 198 x^2-31x+198 = 0 (x-9)(x-22) = 0 ...
*July 22, 2016*

**math**

a(bx-c) = d-(x+e) abx-ac=d-x-e (ab+1)x = ac+d-e x = (ac+d-e)/(ab+1)
*July 22, 2016*

**Math**

Hmmm. 7.8sin (pi/6(t-3)) = 10.29 sin (pi/6(t-3)) = 1.319 <--- ?? I suspect that you have left out a term in the definition of h(t). Fix it and then proceed with the solution.
*July 22, 2016*

**Math**

2 trenches = 3*5 = 15 man-hr 7 trenches = 7/2 * 15 = 105/2 man-hr (105/2 man-hr) / (5 man) = 21/2 hr or, 10 hr 30 min
*July 22, 2016*

**RE**

The only thing you have to remember is that since the two sides of an equation are equal (hence the name), if you do the same thing to both sides, they remain equal. Your goal is to isolate the variable on one side, so the other side is just its value. Now, when you say you ...
*July 22, 2016*

**math**

well, you know that the equation for a parabola with vertex at (0,0) directrix y = -p is x^2 = 4py Your parabola has been shifted so the vertex is at (-2,4), so you want (x+2)^2 = 4p(y-4) Your directrix is at y = 1, which is 3 units below the vertex, so p=3 (x+2)^2 = 12(y-4) ...
*July 22, 2016*

**math**

log1/2(x-1)+log1/2(x+1)-log1/√2(7-x)=1 You seriously need to learn how to use parentheses. Also, the final result will depend on the base of the logarithms. I shall assume base 10. Assuming you meant log(1/(2(x-1)))+log(1/(2(x+1)))-log(1/(√2(7-x)))=1 log (1/(2(x-1...
*July 22, 2016*

**Maths**

the height on the nth bounce is 100*0.8^n So, the geometric sequence for the bounces is a = 100 r = 0.8 Each bounce is a round trip, except for the 0th trip, so the distance traveled is 2*100/0.2 - 100 = 900 ft The real-world distance of course will be slightly less than that.
*July 22, 2016*

**math**

the number who passed either or both is 30+20-8 = 42 so, ...
*July 22, 2016*

**math**

or, since 15 = 3*5, multiply by 5/5 and you have 3/7 = 15/x 15/35 = 15/x x = 35
*July 22, 2016*

**Calculus**

well, x is cut off both sides, and x is the box's height, so v(x) = (18-2x)(12-2x)(x)
*July 22, 2016*

**math**

Divide the $420 into 10 parts of $42 each. A gets 3 parts, or $126 B gets 7 parts, or $294 In order for A to get 180, either B gets 420 or a gets 3/7 of the total, not 3/7 of B's share.
*July 22, 2016*

**Futher maths**

I'll just use x, for ease of typing tanx + 2secx = 2cotx + 3cscx A strange mixture of functions, so I'll just use sine and cos: sinx/cosx + 2/cosx = 2cosx/sinx + 3/sinx (sinx+2)/cosx = (2cosx+3)/sinx So, assuming that cosx and sinx are nonzero, sinx(sinx+2)-cosx(2cosx+...
*July 22, 2016*

**Math**

what's the problem? Just calculate the distance and time as needed, and the average speed is distance/time. For (a), A-B is 25km A-C is 10km So, B-C is 15km C-A takes 1.5 hr B-A takes 3.5 hr stop at C takes 0.5 hr So, the B-C leg takes 1.5 hr 15km/1.5hr = 10km/hr The rest ...
*July 22, 2016*

**English**

zombie apocalypse runaway vehicle fire army ants avalanche chainsaw maniac
*July 22, 2016*

**Math**

if you review the definition of the cotangent function, then you can see that with a height of h, h cot19° - h cot37° = 60
*July 21, 2016*

**Physics**

each bulb is a separate branch of the circuit, and so has the same voltage drop. Since they have the same resistance, each bulb gets a current of 1.5V/6.3Ω = 0.238A Note that 1/Rt = 0.317, so Rt = 3.15 = 6.3/2 Ω
*July 21, 2016*

**math**

one measurement is worth a thousand expert opinions. Buy some chips, fill the jar. Empty them out, count them. In the interest of accuracy, it will be best to eat the chips and repeat with a new batch. Maybe several times!
*July 21, 2016*

**Civics.**

I agree with D, but I'd hardly consider Brazil a smaller country. Its area is bigger than the continental USA, and it has vast natural resources. Granted, a lot of them are in the jungle, and that makes them harder to extract.
*July 21, 2016*

**Msth**

actually, keeping track of the units, 1,130mi / 25mi/gal = _______ gallons Multiply the gallons by $2.60/gal to get the dollars
*July 21, 2016*

**Physics**

G(M)(2M)/(3x)^2 = KGM^2/x^2 2GM^2/9x^2 = KGM^2/x^2 2/9 = K
*July 21, 2016*

**statistic**

Consult your Z table to see how many std away leaves 4.5% Multiply that by 0.36 and add it to the mean. Play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html
*July 21, 2016*

**math**

pair them up in this way: -35,35 -34,34 ... The sum of all those pairs is zero. So, which numbers are left over? Add them up.
*July 21, 2016*

**math**

after a 30% markup the price is cost * 1.30 After a 15% discount, the price is cost * 1.30 * 0.85 = cost * 1.105 That price is $99, so 1.105 * cost = 99 cost = 99/1.105 = 89.59
*July 21, 2016*

**math**

cost * 1.30 * (1-0.15) = 99 cost = 99/1.105 = 89.59
*July 21, 2016*

**Math CSET**

There is no easy way. The actual math formula is simple, but hard to do by hand. I suggest that you just have to know the values for 1,2,3 std from the mean. Just as it is best if you just know the trig values for common angles.
*July 21, 2016*

**Algebra**

Assuming "a rate at x rate per min" means "a rate of x ft per min", then 4000 - xy
*July 21, 2016*

**PHYSICS**

will squash you like a bug.
*July 21, 2016*

**algebra - incomplete**

sorry - you need another equation.
*July 21, 2016*

**Electric Circuits**

I = E/R Now just plug in your numbers.
*July 21, 2016*

**general math**

K(x) = 15.00x for x <= 50 12.50x for 50 < x <= 75 Apparently you had some choices, but they're not here. I got my answer by reading the text provided. How else?
*July 21, 2016*

**math**

LCM(25,30) = 150 minutes 11:00 + 2:30 = 13:30, or 1:30 pm
*July 21, 2016*

**math**

Reiny did this one already. See the related questions below.
*July 21, 2016*

**Physics or Math**

The Toyota goes 350km in 5 hours. The Kia has gone the same distance in 7 hours. So, the Kia's speed must be 50 km/hr
*July 21, 2016*

**math**

for the triangle, 6*5 = 1/2 * 12 * h Now, knowing h, the side length s can be found using s^2 = 6^2 + h^2 For the towers, the distance z is z^2 = 16^2 + (40-10)^2
*July 21, 2016*

**Physics**

distance = time * speed. So, 5*70 = (5+2)*x
*July 21, 2016*

**Calc**

we want to maximize xyz subject to the constraint that 5xy+3(xy+2xz+2yz) = 1000 Using Lagrange multipliers, we find that x=y, and λ=2.1516 and z=4λ That means a local max occurs at (6.455,6.455,8.607) A nice article on Lagrange multipliers, with an example similar to...
*July 20, 2016*

**Geometry**

see earlier post better yet, graph the two functions and see the shifts
*July 20, 2016*

**Geometry**

I think she meant y=(x−5)^2+5 → y=(x−0)^2+0 shift left 5 and down 5
*July 20, 2016*

**Chemistry**

DrBob222 did it last night. See the related questions below.
*July 20, 2016*

**maths - sloppy**

The rectangle is x meters what? wide? long? do you mean x m^2, the area?
*July 20, 2016*

**Math**

There are 4 cubes per foot, so in terms of cubes, the prism is 8/14 x 4 x 5 Since you want whole cubes you are out of luck, since 2/14 < 1/4, the size of a cube. I suspect a typo. Fix it and then apply the logic.
*July 20, 2016*

**Math**

draw your triangle. secθ = r/x and x<0, so θ is in QII or QIII x = -3 r = √20 y = ±√11 Now just recall that tanθ = y/x, so it will be ±√11/3, depending on the quadrant.
*July 20, 2016*

**Physics**

I'm sure you have seen examples of this simple circuit. (a) R = 2+3 (b) 1/R = 1/2 + 1/3 I = E/R in each case.
*July 20, 2016*

**physics**

2r/πr = 2/π π/2 is the ratio between its distance traveled (πr) and its displacement (2r).
*July 20, 2016*

**math**

right you are. Should be "greatest." If I had to choose (and I don't) I'd assume sloppiness and pick 11.
*July 20, 2016*

**mathematics**

I'd say zero, since today is Wednesday!
*July 20, 2016*

**math**

a = b*l = b * b^2 = b^3 da/dt = 3b^2 db/dt 40 = 3*64 db/dt db/dt = 5/24 l = b^2 dl/dt = 2b db/dt = 2*8 * 5/24 = 10/3
*July 20, 2016*

**math**

hmmm. where is D? If your inequalities hold, then clearly CD < AC < AD
*July 20, 2016*

**math**

draw a diagram. Review your basic trig functions. Now it is clear that if the height is h ft, h cot 78°15' + h cot 59°47' = 500
*July 20, 2016*

**Physics**

.001s * 340m/s = 0.340m
*July 20, 2016*

**valuemath**

No ratio given for cows and goats. But, the sheep:goats ratio is 15:20
*July 20, 2016*

**Math**

4a(b) = a(2b)-24 4(b^2-2b) = (2b)^2-2(2b)-24 4b^2-8b = 4b^2-4b-24 4b = 24 b = 6
*July 19, 2016*

**Math**

e*f is constant, so you want e such that (1/3)e = 9*3
*July 19, 2016*

**Math**

Looks like Benjamin to me, but do it the same way: p^1/3 = (8x)^1/6 p^2 = 8x x^-1/2 = 4^-1/4 x^-2/4 = 4^-1/4 x^-2 = 4^-1 x^2 = 4 x = 2 p^2 = 16 4y = |p-8| 4y = 8 y = 2
*July 19, 2016*

**Math**

4 - 3y < 10 3y > 14 y > 14/3 = 4 2/3 -y-8 > -14 y < 6 so, how many integers are there between 4 2/3 and 6?
*July 19, 2016*

**math**

yes, you do (-4-6)^2 + (-14-10)^2 = 10^2+24^2 = 26^2
*July 19, 2016*

**math**

The result above is the length of the path from home to courthouse and then on to office. the distance z from home:(6,10) to office:(-4,-14) is This is just a scaled-up 5-12-13 triangle, being 10-24-26.
*July 19, 2016*

**math**

presumably we want to find the original area to be shoveled. If that was x, then x(1/5 - 2/5) = 200
*July 19, 2016*

**maths**

If he marks up r%, then (1+r)c*.70 = 1.1c 1+r = 1.1/.7 r = 1.1/.7-1 = 0.57 = 57% or 4/7 Check: cost = 14 1.57*14 = 22 22*.7 = 15.4 = 14 * 1.10
*July 19, 2016*

**math**

with respect to what? Let's do r if y' = dy/dr, 2yy' = 4p y' = 2p/y y" = -2p/y^2 y' = -4p^2/y^3
*July 19, 2016*

**Physics**

after a distance s, v = 2√(5s+10) - 10
*July 19, 2016*

**Physics**

the k component has doubled. So, the others must also, giving 4i+6j+2k
*July 19, 2016*

**Physics**

just check and see that A = 3B
*July 19, 2016*

**Physics**

R = 2h
*July 19, 2016*

**Physics**

the article in wikipedia gives the formulas, which I'm sure you already have. Just divide H/R and simplify. https://en.wikipedia.org/wiki/Trajectory
*July 19, 2016*

**Physics**

see related questions below. just figure how long it takes to fall, then calculate the distance flown in that time.
*July 19, 2016*

**Physics**

just figure the mass of water, and recall that water has a density of 1g/cm^3 No idea what the unknown liquid has to do with anything.
*July 19, 2016*

**pre cal**

∛(2/(1-x)) (-7±√(4x^2+49))/2 which branch depends on the domain of f(x)
*July 19, 2016*

**pre cal**

If the point (40,3) is on the graph of y=f(x), what point must be on the graph of y=8f(8x) (5,24) just solve x+13 = -12 x = -25 y = -(-8/4-13) = 15 So, the new graph must contain (-25,15) similarly for the other one.
*July 19, 2016*

**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*