Monday

July 25, 2016
Total # Posts: 42,055

**physics**

surely you have a formula which gives this value. If not, see the excellent article in wikipedia on "trajectory"
*June 5, 2016*

**Math**

MP*.84 = CP*1.05 MP/CP = 1.05/0.84 = 1.25 so, the original markup was 25%
*June 5, 2016*

**MATH**

Draw a diagram. It is clear that the distance of chord from center: d^2 + (6/2)^2 = 5^2 the chords are 2d apart.
*June 5, 2016*

**maths**

18*2 + x = 27*3
*June 5, 2016*

**itc c++**

what, you don't have a c++ system?
*June 5, 2016*

**math**

The beam length b is b^2 = 192^2 + (70+10)^2
*June 5, 2016*

**Math - surface area**

well, the area is πr^2 = 4π yd^2 a first approximation is thus 4π*13
*June 5, 2016*

**maths**

24^2 + 48^2 + h^2 = 56^2
*June 5, 2016*

**math**

3b+c = 14t b+6t = 1c so, find c in terms of t: c = 14t-3b = 14t-3(c-6t) c = 14t-3c+18t 4c = 32t c = 8t
*June 5, 2016*

**math**

If the 4 groups have w,x,y,z respectively, then w = x+4 x = y-1 z = 2x w+x+y+z = 20 Now just crank it out.
*June 5, 2016*

**Math(Please Help Assignment Due Today)**

man. of all the possible sets, AAA does not guarantee congruence -- only similarity.
*June 4, 2016*

**Math(Please Help Assignment Due Today)**

well, you've posted this a few times. Did you think of googling your question? Many hits. Maybe you could start here: http://www.regentsprep.org/regents/math/geometry/gp4/ltriangles.htm
*June 4, 2016*

**math**

not quite. You figured the straight-line distance, but that does not answer the question. Read it again carefully.
*June 4, 2016*

**physics**

The ratio of KE after the bounce to before the bounce is 1/2 m(.8v)^2 ----------------- 1/2 mv^2 = .8^2 = .64 so, the ball will bounce .64 as high as the original height
*June 4, 2016*

**geometry**

so, add 5 to x and subtract 4 from y. Not so hard, eh?
*June 4, 2016*

**maths**

f(x) = 2x Looks like y= ax, with a=2 or y = 2f(x) if f(x) = x not quite sure just what it is you're asking. enter your expression at wolframalpha.com and see the graph.
*June 4, 2016*

**science**

the difference is .11 hours .11/3.15 = 0.0349 ≈ 3.5%
*June 4, 2016*

**mathematics**

As always, draw a diagram. AB/18 = tan35° CD^2 = 18^2 + 24^2 from C, tanθ = AB/24 from D to C, tanθ=24/18, so the bearing is 360-θ
*June 4, 2016*

**mathematics**

well, the common denominator is 2(y-1), so that gives you 1(y-1)+3(2) ----------------- 2(y-1) ...
*June 4, 2016*

**Math**

but, you know how to count money, right? 7 quarters = $1.75 need 11 more coins, so start using smaller ones. 6 quarters and 5 nickels = $1.75 need 7 more coins 5 quarters and 10 nickels = $1.75 need 2 more coins. 4 quarters and 15 nickels - $1.75 need 2 coins less 4 quarters, ...
*June 4, 2016*

**Math-Calc**

so, the critical numbers are the values where f'(r) = 0, right? A fraction is zero if its numerator is zero. So, what is r if 7 - 10r^2 = 0?
*June 4, 2016*

**Statistics**

Never mind -- I'm bored already.
*June 4, 2016*

**maths again plz**

since 1 hour is 60 minutes, 35'25" = 0.59 of a complete circle. the circumference is 2pi*r, so the distance traveled is 2pi*8.8*0.59 = 32.64 cm
*June 3, 2016*

**maths-need help asap**

yes, with no radius, it's difficult to find the volume. The problem has been garbled, apparently. Both the cylinder and the cone are incompletely specified. And that doesn't even get into the bad grammar...
*June 3, 2016*

**maths-need help asap**

just find the volume in cm^3 Then recall that 1L = 1000cm^3
*June 3, 2016*

**math**

(5/3)^2 * (3/4)^2 = (5/4)^2 = 1.5625
*June 3, 2016*

**Math**

well, let's see... cos(x) starts at the top, and has amplitude 1. You want to start at the bottom, with amplitude 30. cos(kx) has period 2π/k. You want period 2. So, what is k?
*June 3, 2016*

**algebra**

xy=20
*June 3, 2016*

**Maths**

just compute the lengths of the sides. Two of them are equal.
*June 3, 2016*

**Calculus**

nope, you need k * f(x) and C alone. ∫k*f(x)+C dx = ∫k*f(x) dx + ∫C dx = k∫f(x) dx + ∫C dx your answer is ∫k(f(x)+C) dx
*June 3, 2016*

**Math (Parametrics)**

x=cos(t) y=sin(t) This will start at (1,0), but you want to start at (0,1) Since cos(0) = 1, you need y = cos(t) x = sin(t) Now you can see that as t->pi/2, y goes down and x goes to the right. That makes it clockwise.
*June 3, 2016*

**college Algebra**

so close! But 2+6≠9 The roots are irrational.
*June 3, 2016*

**Calculus**

Recall that if F(x) = ∫[a,x] f(t) dt, F'(x) = f(x) so, F'(x) = f(x) = cos(x^3)
*June 3, 2016*

**Math Urgent Please Help**

RST has sides RS=4, RT=3, ST=5 If the other triangles are ABC, then we have (a) AB=4, AC=√20, BC=√20 As you can see, the various sides are not all the same multiple of RST's sides. You will need to check the others to see whether their sides are in the ratio 4:...
*June 3, 2016*

**math**

42p = 4-2p+8 44p = 12 ...
*June 3, 2016*

**science**

the resultant has magnitude √(23^2 + 41^2) and direction θ where tanθ = 23/41
*June 3, 2016*

**Discriminant**

(x-y)(x+y) = x^2-y^2 you have x = b y = √40 = 2√10 so, b^2-40 = (b+√40)(b-√40) = (b+2√10)(b-2√10)
*June 3, 2016*

**Alpha, beta**

no; fractions are perfectly acceptable. Most folks like to get rid of them, though, so the second form makes them more comfortable. You could just as well have used any of x^2/7 - 2x/7 + 11/63 = 0 5x^2 - 10x + 55/9 = 0 90x^2 - 180x + 110 = 0
*June 3, 2016*

**Chemistry**

how many on a single atom? Then multiply that by .002 * 6.023x10^23
*June 3, 2016*

**Algebra 1**

2x+4 <= 14 2x <= 10 x <= 5 so, 5 is the largest possible number. 2*5+4 = 14. Any number larger than 5 makes the expression more than 14.
*June 3, 2016*

**Math-Calc**

see earlier post
*June 2, 2016*

**Calc-Math**

If you don't even know where to begin, you must not have read the section on this topic. It says that the limit of f(x)/g(x) = f'(x)/g'(x) so, your limit is just (ln3 * 3^x - ln6 * 6^x)/1 = (ln3-ln6) = ln(3/6) = -ln2
*June 2, 2016*

**calculus**

without calculus, the distance from the point to the line is |4(-2)+2(-1)+5|/√(4^2+2^2) = √5/2 Using calculus, we have the distance z from (-2,-1) to (x,y) is z^2 = (x+2)^2 + (y+1)^2 But y = -(4x+5)/2, so z^2 = (x+2)^2 + ((-(4x+5)/2)+1)^2 z^2 = 5x^2 + 10x + 25/4 z...
*June 2, 2016*

**Geometry**

The x=15 is ok Not sure what the last set of values is for, but if they are for the 1st problem, no good. x^2 + (5-x)^2 = 25 x^2 + x^2-10x+25 = 25 2x^2-10x = 0 2x(x-5) = 0 x = 0 or x=5 So, the points of intersection are (0,5) and (5,0)
*June 2, 2016*

**Geometry**

well, y = 5-x, so x^2 + (5-x)^2 = 25 now just expand and solve the quadratic.
*June 2, 2016*

**Algebra**

x^3-5x^2+2x+8 ----------------- = x^2-3x-4 x-2
*June 2, 2016*

**Geometry**

right
*June 2, 2016*

**Geometry**

Assuming a typo, and you meant PN, we have PM/ZX = PN/ZY so, (x+5)/30 = (4x-10)/75 Now just solve for x.
*June 2, 2016*

**Calculus**

I just noticed that you did not specify that the y-axis formed part of the boundary. Without that condition, the horizontal strips extend leftward forever. Of course, you may have mixed up x and y in places, so ...
*June 2, 2016*

**Calculus**

This is most easily done by integrating on y, using horizontal strips. a = ∫[-1,3] x dy = ∫[-1,3] (8+2y-y^2) dy
*June 2, 2016*

**Math(Assignment due today)**

sounds like the ramp rises at a 4.7° angle, so it's ok.
*June 2, 2016*

**Pre-Calculus**

enter your coefficients at the url below to see all the details: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*June 2, 2016*

**Polynomials and properties of exponenets**

I get AC?BD
*June 2, 2016*

**Mathematics**

if the quiz is counted more than the other grades, things get more complicated. If the quiz counts as much as all the rest, then the final grade would be (88+95)/2 = 91.5 I suspect there is missing information here.
*June 2, 2016*

**Physics**

they both travel with the same speed. So, a longer wavelength means it oscillates more slowly. Recall that v = λf 3λ means f/3 to get the same v.
*June 2, 2016*

**Pre-Calculus**

next time, show your work, so we can find your error. From equation 1, x = 2y-5 plug that into #2, and you have x^2+y^2 = 25 (2y-5)^2 + y^2 = 25 5y^2 - 20y + 25 = 25 5y(y-4) = 0 y = 0 or 4 now you can find x values as needed, from either equation. http://www.wolframalpha.com/...
*June 2, 2016*

**Polynomials and properties of exponenets**

D,A,C,D Looks like some serious review is in order.
*June 2, 2016*

**Geometry**

Time to review the special angles: sin(30°) = 1/2 so, √sin(30°) = 1/√2 also, cos(30°) = √3/2
*June 2, 2016*

**algebra**

Reiny responded to this earlier, at http://www.jiskha.com/display.cgi?id=1464879381 If you want to pin it down more, there must be some other constraints.
*June 2, 2016*

**Pre-Calculus**

you got c correct, but did not express the coordinates of the foci. c = ±5 where is the center of the ellipse? Is the major axis horizontal or vertical?
*June 2, 2016*

**Math**

correct
*June 2, 2016*

**Pre-Calculus**

you are correct as far as you went, but recall that n*ln(x) = ln(x^n). 2lnx - 6lny + 1/3ln e^12 = ln(x^2) - ln(y^6) + (1/3)(12) = ln(x^2/y^6) + 4 = ln(e^4 x^2/y^6)
*June 2, 2016*

**5th Grade Math - Urgent Part II**

1,000,000 is the only number with prime factorization 2^6 * 5^6 = (2*5)^6 = 10^6 64 is 2^6 but has no factors of 5.
*June 2, 2016*

**Pre-Calculus**

your function is just a polynomial. The domain of all polynomials is (-∞,∞)
*June 2, 2016*

**algebra**

since distance = speed * time, 6x + 6(x-20) = 624
*June 2, 2016*

**MATH**

They gave you the functions. Did you graph them as suggested? Here are the lines: http://www.wolframalpha.com/input/?i=plot+y%3D25%2B10x+,+y+%3D+18%2B15x Now you can surely answer the questions.
*June 2, 2016*

**Trigonometery**

no one is assigned to sit here and watch for problems. We have lives, too, and when we get a chance, we check in. As you know, the function a sin(kx) has amplitude a and period 2pi/k, so you can use your requirements to produce the function -4sin(8x) But you probably figured ...
*June 2, 2016*

**match**

apparently you have knowledge about ditches and absorption rates which you have not shared here.
*June 2, 2016*

**Calculus**

So, each square has base and height e^-x Thus, the volume, adding up all those thin squares, is ∫[0,2] (e^-x)^2 dx = ∫[0,2] e^(-2x) dx let u = 2x, and that becomes (1/2)∫[0,4] e^-u du ...
*June 2, 2016*

**Physics**

wrong
*June 2, 2016*

**math**

(1+r)^12 = 2 r = 2^(1/12)-1
*June 2, 2016*

**Math**

I assume you really meant 1/(x-1)+1/(x+1) ------------------ 1/(x-1)-1/(x+1) cross-multiply to put top and bottom over a common denominator of (x-1)(x+1) Then since the same denominator occurs top and bottom, it can be discarded, just as (2/3)/(5/3) = 2/5 now you have (x+1)+(x...
*June 2, 2016*

**Math**

gibberish
*June 2, 2016*

**Maths**

kx^2-5x+k is not a cubic polynomial.
*June 2, 2016*

**physics**

Since F=ma, the acceleration of the car is 1/5 gravity. So, how long does it take the car to move 20cm, under (1/5)g acceleration? s = 1/2 at^2
*June 2, 2016*

**Math Please Help Quick**

.20 * 20 = ?
*June 2, 2016*

**math**

t+r = 800 (3/4)t + (5/6)r = 800-192 to find r, substitute for t: (3/4)(800-r) + (5/6)r = 608 (1/12)r + 600 = 608 r/12 = 8 r = 96
*June 2, 2016*

**math**

if you google manual cube roots, you will find several nice explanations of how to extract roots by hand. It's not worth the effort, since calculators are so handy these days. Use your calculator to evaluate 36.13^(1/3) power
*June 2, 2016*

**maths**

draw a diagram. review your basic trig functions. Now it is clear that 2.5/x = cos60° now just solve for x, the length of the ladder.
*June 2, 2016*

**Math Year 10 - Simultaneous equations**

c = 2s 2c+4s=104 now solve for c
*June 2, 2016*

**Mathematics**

It'd be nice to have some of your work to look at, eh? 3/x + 5/y = 4 9/x + 4/y = 5 It gets messy to try and solve for x or y, so solve for 1/x instead. 1/y = (4-3/x)/5 thus, 9/x + 4/5 (4-3/x) = 5 45/x + 16 - 12/x = 25 33/x = 9 1/x = 9/33 = 3/11 so, x = 11/3 now plug in to ...
*June 2, 2016*

**Figurs and Numbers**

12% = 0.12 spending means that amount is subtracted. So, subtract .12 twice. Having done that, subtract another 25% = 0.25, and the remainder is 2010. Then find x, the original amount which leaves that remaining amount. Finally, knowing x, 25% of 57% of that amount is what was...
*June 2, 2016*

**Figurs and Numbers**

x(1-.12-.12)(1-.25) = 2010 .76*.75x = 2010 x = 3526.32 x * .76 * .25 = $670.00 on education
*June 2, 2016*

**Pre-Calculus**

well, it could be (x+1)(x-7)(x^2-2) = what you wrote. extra credit: are there any others?
*June 2, 2016*

**Geometry**

I agree. It looks like a syllogism, but there are too many things wrong.
*June 2, 2016*

**Sxiences**

recall that F = ma now just plug in your numbers to get m.
*June 1, 2016*

**Spanish**

correct
*June 1, 2016*

**MAth**

simple interest: 200*.06*2
*June 1, 2016*

**Chemistry**

depreciation
*June 1, 2016*

**Chemistry**

two errors, DrRebel: (0.693/3.8) ≠ 0.8663 it was 98.4, not 94.4
*June 1, 2016*

**Chemistry**

98.4 * (1/2)^(19/3.8) = 3.075 g
*June 1, 2016*

**Mathematics**

for the perimeter, since p = 2(length+width) p is even, since it is a multiple of 2.
*June 1, 2016*

**Algebra**

How much more is 9 than 7? You do it by finding the difference: 9-7 so, do this the same way: (9x+8)-(5x+6) ...
*June 1, 2016*

**math**

divide that by 2, since it takes two hands to shake once.
*June 1, 2016*

**Math**

x:9=2/3:36 x*36 = 9 * 2/3 36x = 6 x = 1/6 = 0.1666 or, x/9 = (2/3)/36 x/9 = 2/108 x/9 = 1/54 x = 9/54 = 1/6 maybe you should try some other proportions with less complicated numbers, to learn the method and why it works.
*June 1, 2016*

**Math**

you have to subtract the width of the frame, both top and bottom. The remaining height is occupied by the picture 5 2/3 * 2 = 10 4/3 = 11 1/3 now subtract that from the overall height, and you have 25 5/6 - 11 1/3 = 25 5/6 - 11 2/6 = 25-11 + 5/6 - 2/6 = 14 3/6 = 14 1/2
*June 1, 2016*

**Science - Chemistry**

Kind of depends on the size of the diamond, wouldn't you say?
*June 1, 2016*

**Math please help**

note that as x grows by 2, y falls by 1. That gives you a slope of -1/2. So, start with y = -1/2 x But, if you plug in x=2, that gives y = -1/2 (2) = -1 But in fact, y=1. So you need to add 2, giving you y = -1/2 x + 2 or, y = (4-x)/2 Use the other values of x and y to see ...
*June 1, 2016*

**Pre-Cal: Plz help!**

Go to Reiny's url and tweak the input until it agrees with what you intended. It's probably just a combination of typos.
*June 1, 2016*

**math**

me either, but recall that 1L = 1000cm^3, so find your volume in cm^3 and divide by 1000
*June 1, 2016*