Wednesday

October 1, 2014

October 1, 2014

Total # Posts: 25,381

**math**

P = a-c = (a+b)-(b+c) = 49-13 = 36
*September 5, 2014*

**algebra**

y increases by 4 when x increases by 1. So, look for something like y = 4x+b Now, when x=1, y=0, so we end up with y = 4x-4
*September 5, 2014*

**algebra**

the height is the y-value at the vertex, where x = .658/.000814 Since y = x(.658-.000407x) the roots are at 0 and 1616.7 The bridge spans that distance
*September 5, 2014*

**algebra**

first rearrange the terms so you have 2x^2 + 2x - 5 = 0 Now just plug in the formula, where a = 2 b = 2 c = -5 x = (-2±√(2^2 + 4*2*5))/(2*2) = (-2±√44)/4 = (-1±√11)/2
*September 5, 2014*

**math**

using the same ratio, x/125 = 400/20000 x = 2.5
*September 5, 2014*

**Physics**

(a) 31.1t = 1/2*4.11t^2 t = 15.134 seconds Now use that t for parts (b) and (c)
*September 5, 2014*

**Physics**

see related questions below, and change the numbers as necessary. The key is to separate the 2.2 seconds into the falling time and the return time.
*September 5, 2014*

**math**

review scientific notation. There is a number and a power of 10. the number must be between 1 and 10. (Less than 10) When adding, the powers of 10 must be the same, just as you need a common denominator to add fractions. Then you can just add the numbers as usual, keeping the ...
*September 5, 2014*

**Math**

the chance it will not snow on a day is 3/5, so for two days, that is 3/5 * 3/5 = 9/25
*September 5, 2014*

**Math**

the ratio of 3.25in : 4cm for the short side is 3.25*2.54/4 = 2.07 close enough for jazz. Now use that scale factor to enlarge 4.6cm. Probably should express the answer in inches, as well, since that was the original frame size unit. Actually, you don't need the scale ...
*September 5, 2014*

**math**

just drag out your formula for the area of a circle: A = πr^2 In this case, r = 7 yd, so A = π(7 yd)^2 = 49π yd^2
*September 5, 2014*

**Operating Systems**

pages are accessed in the order acbd*a*c*b*d*e*f* Bad luck, that.
*September 4, 2014*

**math**

each photo is 2x2, so 2*60 = 120
*September 4, 2014*

**Math**

you can solve for x or for y. Which is of interest to you?
*September 4, 2014*

**math word problem**

300(1+.04)^5
*September 4, 2014*

**Pre-Calc**

As usual, draw a diagram. It is clear that if the height of the mountain is h, and the tower is at a distance x from the mountain, (h-180)/x = tan 21°35' h/x = tan 24°48' Eliminate x and you have (h-180)/tan21°35' = h/tan24°48' Now just solve for h
*September 4, 2014*

**Geometry**

I'd say 56 and 75 Maybe a bit more context would be helpful...
*September 4, 2014*

**AP Physics**

total distance: 7.7*4.5*60 + 2.8*2.8*60 = 2549.4 m total time: (4.5+2.8)*60 = 438 s so, avg velocity is 2549.4/438 = 5.8 m/s
*September 4, 2014*

**math help!!**

you have the difference of two squares: (a/6)^2 - (b/7)^2 So now the factoring is easy, right?
*September 4, 2014*

**math**

For the 4th test, 79+97+85+x = 4*85 so, x = 79 Then, for the 5th test, 4*85 + y = 5*(85+3) so, y=100
*September 4, 2014*

**math**

r = 6w+1 r+w = 50 so, r = 43
*September 4, 2014*

**math**

-10 -3 5 16 vs -3 5 -10 16 The second list would be unchanged if the new numbers were used.
*September 4, 2014*

**Math**

no way to solve for anything without an = sign
*September 4, 2014*

**Alhebra1**

3^2+(5+2)•4- 6/3 First, parentheses: 3^2+7•4-6/3 Next, powers: 9+7•4-6/3 Next, multiplication and division: 9+28-2 Finally, addition and subtraction: 35 As that is not one of the choices, I suspect a typo. Find it, fix it, and then follow the same steps.
*September 4, 2014*

**Math**

s = 2j+5 i = 4j s+j+i = 96 Now solve, using your method of choice.
*September 4, 2014*

**algebra**

8+3x(6-4)-1=13
*September 4, 2014*

**physics**

the height y of the ball at distance x is y = x tanθ - g/2v^2 sec^2 θ x^2 so, we want to solve for v in 110 - 9.8/v^2 * 110^2 = 0 v = 32.83 m/s
*September 4, 2014*

**math**

since the amount drops by 1/2 every T, the function is f(t) = (1/2)^(t/T) But, 1/2 = e^-ln2, so f(t) = (e^(-ln2))^(t/T)) = e^(-ln2/T t) = e^(kt)
*September 4, 2014*

**math rounding**

before we can do much, you have to fix "The value of the thousands digit is double that of the the thousands digit."
*September 4, 2014*

**Math**

review what supplementary angles are, then solve 10x-25 + 15x+50 = 180 Now that you have x, evaluate the two angles.
*September 4, 2014*

**math**

If there were already n tests, then if Diane scored d and Peter scored p, then with the current average of a, n*a + 97 = (n+1)(90) n*a + 73 = (n+1)(87) so, we can eliminate the a and have (n+1)(90)-97 = (n+1)(87)-73 (n+1)(3) = 24 n+1 = 8 n = 7
*September 4, 2014*

**algebra**

there is no solution. If you subtract 3x from both sides, you have 0 = -3 Is there a typo?
*September 4, 2014*

**Geometry**

GB has length √25 GF has length √85 I expect you can compare those Do others in like wise.
*September 4, 2014*

**Algebra1**

[(40+5)-3^2]÷9•2 [45-9]÷9•2 36÷9•2 4•2 8
*September 4, 2014*

**Math**

y = x^2+16x+64 = (x+8)^2 + 0 so, the vertex is at (-8,0)
*September 4, 2014*

**Math**

y = x^2+16x+64 = (x+8)^2 + 0 so, the vertex is at (-8,0)
*September 4, 2014*

**math**

ages now: t and g 16 years ago, (g-16) = 8(t-16) 8 years from now, (g+8) = 3(t+8) Hmmm. solving those two equation, I don't get integer solutions. That's ok, but unusual. If I have gotten something wrong, fix it and follow through, finishing with the ratio (t-8)/(g-8) ...
*September 4, 2014*

**Math**

looks good to me.
*September 4, 2014*

**Math**

Review conditionals: if hypothesis then conclusion 1. D 2. D
*September 4, 2014*

**algebra**

the point-slope form tells you that y-3 = 2(x-1) Rearrange things to get y = 2x + 1
*September 4, 2014*

**(Please Help!) Analytic Geometry**

google it - wikipedia has a good discussion
*September 4, 2014*

**Ms Sue Please Help ! Analytic Geometry**

what do you mean "identify the points"? 9x^2 + 4y^2 -54x-16y + 61 =0 9x^2-54x + 4y^2-16y = -61 9(x^2-6x) + 4(y^2-4y) = -61 9(x^2-6x+9) + 4(y^2-4y+4) = -61 + 9*9 + 4*4 9(x-3)^2 + 4(y-2)^2 = 36 (x-3)^2/4 + (y-2)^2/9 = 1 ellipse with major axis vertical, semi-axes of ...
*September 4, 2014*

**science**

you know that the height at time t seconds is h(t) = 24 + 24.5t - 4.9t^2 so, just solve for t when the stone hits the ground (its height is zero).
*September 4, 2014*

**Physics**

Hmmm. bobpursley is usually right on these matters. I'll have to think on it a bit to see why the initial height makes no difference.
*September 4, 2014*

**Physics**

the time for the pellets to hit the ground is A: h + 36.3t - 4.9t^2 B: h - 36.3t - 4.9t^2 I expect you will need to know h (the height of the cliff) to solve for the two values of t and take their difference. A: t = (-36.3 ±√(1317.69+19.6h))/9.8 B: t = (36.3 &...
*September 4, 2014*

**Math (data)**

good riddance to the bums.
*September 4, 2014*

**algebra**

the arrow points to the smaller number 6 < x means six is less than x x > 2 means x is greater than 2 <= means less than or equal >= means greater than or equal So, you want -6 < x < 6 think of the point of the arrow as small, so it's next to the smaller ...
*September 4, 2014*

**MATH**

one way is to convert all to decimals and compare. the other way is to recall that for a given numerator, the larger the denominator, the smaller the value. That is 1/10 is less than 1/7, and so on Now, you have several numbers which are all greater than 2 by some amount Those...
*September 4, 2014*

**Math**

if there are x yellow cars, there are 9x white cars so, add them up: x + 9x = 40 10x = 40 x = 4 Now you know how many yellow cars there are, so you can figure out how many white ones there are.
*September 4, 2014*

**math**

the domain of y is all real numbers except odd multiples of 1/2. So, your logic is sound, but the domain is all reals except 1/2 + k for k in Z.
*September 4, 2014*

**Mathematics for business & finance**

sounds like a good deal. was there a question somewhere in there?
*September 4, 2014*

**thank u**

we aim to please...
*September 4, 2014*

**Algebra 2**

since the vertex occurs at x = -b/2a, y = a(-b/2a)^2 + b(-b/2a) + c = b^2/4a - b^2/2a + b = -b^2/4a + c
*September 4, 2014*

**7th grade math**

you want 3+x > 0 so, subtract 3 from both sides to get x > -3 so, pick any value greater than -3
*September 3, 2014*

**geometry**

6x+17 Maybe you could provide a bit more context here ...
*September 3, 2014*

**Math**

It is in fact C D is just a quadratic in (2/x-4), because if you substitute u=2/x-4, you have just 3u^2+5u-2=0 It is C because as you say, there is not a term with twice the exponent of the other.
*September 3, 2014*

**math**

25q + 5(2q) + 1(3q) = 760 38q = 760 q = 20 so, 20 quarters, 40 nickels, 60 pennies
*September 3, 2014*

**MATH1112**

In the first case, we have (1+p)(1-q) In the second case, we have (1-q)(1+p) Looks the same to me, and for the stated reason.
*September 3, 2014*

**Math**

since the height:shadow ratio is the same for both, h/21 = 68/96
*September 3, 2014*

**Math 112**

Bogus. 1% = 0.01 because "percent" means "per 100" 1 per 100 = 1/100 = 1% .01% means .01/100 = .0001
*September 3, 2014*

**Honors Pre Calculus**

Not sure what the little ￼ characters mean, but unless (1-sinx)^2 = |cosx| it can't be true.
*September 3, 2014*

**alegbra**

the degree is the sum of all the powers of variables. If no power is given, then assume it is 1. SO, the terms have degrees 3,2+1,2,1+2 The degree of the polynomial is the highest degree among the terms. I see no like terms to combine
*September 3, 2014*

**math**

Ratios are written 3:4, not 3.4 Initially, r/y = 3/4 Later, (r-3)/(y-6) = 4/5 Solve those two equations to get r=27, y=36
*September 3, 2014*

**AP Physics**

total distance: 8.5-3.6 = +4.9 cm total time: 4.5 - (-1.5) = 6.0s avg velocity: +4.9/6.0 cm/s
*September 3, 2014*

**math help!!**

you have the difference of two squares (3n)^2 - 5^2 That should help.
*September 3, 2014*

**algebra**

-2a^2 / 24ab is not -12ab It is -a/12b because you have -(2a)(a) / (2a)(12b) and the 2a's cancel 6ab^2/24ab = (6ab)(b) / (6ab)(4) = b/4 12a^2b^3 / 24ab = (12ab)(ab^2) / (12ab)(2) = ab^2/2 Looks like you have some serious practice ahead. You can enter your expressions in ...
*September 3, 2014*

**Physics**

You know that the initial height is the constant term. So, the building is 50m tall The ball hits the ground when the height is zero. So, just solve for t when h=0 I assume you want to know how long the ball is at least 55m above the ground. It is only at 50m for an instant. ...
*September 3, 2014*

**algebra**

√(2-w) = w^2 2-w = w^4 w^4+2w-2 = 0 The solutions to that are not trivial. So, assuming you meant √2 - w = w √2 = 2w 2 = 4w^2 w = ±1/√2 Better try again. Ignoring the first two lines, once you get to (w+2)(w-10) I'm sure you meant (w+2)(w-1...
*September 3, 2014*

**Math**

the questions posted here need to provide full context. using those three digits, the only number which is even and less than 300 is 254
*September 3, 2014*

**Math**

which "other" number?
*September 3, 2014*

**Honors Pre Calculus**

assuming the person starts at the wheel's lowest position when t=0, that means that f(t) will look something like f(t) = -cos(t) The radius is 25 feet, so that makes it f(t) = -25cos(t) The axle is 25+4=29 feet off the ground, so f(t) = 29-25cos(t) since cos(kt) has period...
*September 3, 2014*

**AP Physics**

116 km/hr * 1hr/3600s = 116/3600 km = 0.03222 km
*September 3, 2014*

**Science independent variable**

other things being equal, I'd say the temperature.
*September 3, 2014*

**algebra - repost**

I assume that x^ means x^2. Usually the caret requires a numeric exponent. After all, it could be cubed (x^3) or something else. Given that, we have (-2a^2 + 6ab^2 - 12a^2b^3) / -24ab The rest is very difficult to parse. Why not try reposting using clear notation as I did ...
*September 3, 2014*

**Math. Help Thanks!**

since the plane descends 100 feet as it travels 5000 feet, clearly the slope is -100/5000 = -0.02 so, since y=100 when x=0, y = 100-0.02x Note that when x=5000, y = 0, and we have touchdown.
*September 3, 2014*

**algebra 2**

Use a number with exponents. 4(x-1)^2 - 8 4(x^2-2x+1)-8 4x^2-8x+4-8 4x^2-8x-4 You must multiply the 4 by each term in the parentheses, not just the first one. 4(2+6) = 4*2 + 4*6 = 8+24 = 32 NOT 4(2+6) = 4*2+6 = 8+6 = 14 after all, 2+6=8, and 4*8 = 32
*September 3, 2014*

**11 Physics**

surely you have similar question that you can study. You know that the initial height is the constant term. So, the building is 50m tall The ball hits the ground when the height is zero. So, just solve for t when h=0 I assume you want to know how long the ball is at least 55m ...
*September 3, 2014*

**Algebra 2**

sorry (-3)^2 = (-3)(-3) = +9
*September 3, 2014*

**math**

If the 4th person invested y, then 1,000,000 + x + 2x + y = 1,100,000 But y is as much as the other three together, so y+y = 1,100,000 y = 550,000 I'm sure you can now find the other answers.
*September 3, 2014*

**Math**

You cannot locate √-15 on the real number line, because it is not a real number. √(94^3) = (√94)^3 = 9.695^3 = 911.364
*September 3, 2014*

**Math**

hint: 7 > 6 > 5
*September 3, 2014*

**math**

clearly each pack of wax has enough wax to make 2 candles (14/7 = 2). So, now can you figure how many candles can be made from 8 packs of wax?
*September 3, 2014*

**math**

1.50/3.75 = 0.4 = 40%
*September 3, 2014*

**Math**

First, you have to know how to factor numbers. 55 = 11*5 22 = 11*2 The only factor which is common to both is 11, so you have 11*5 + 11*2 = 11(5+2)
*September 3, 2014*

**maths**

If you draw a diagram, and mark the spot on the rim, you can draw a radius to the point. That radius will be the hypotenuse of a triangle, such that (r-1)^2 + (r-8)^2 = r^2 so, r=13 Hence, the diameter is 26 inches
*September 3, 2014*

**math**

Just to be clear, the number has to be at least 1.0 and less than 10. In interval notation that would be a number in [1.0,10.0)
*September 3, 2014*

**Physics**

original acceleration is a 1/2 at^2 = 37 v = at new acceleration is 2a since v = 2at, new time is (2.3v)/(2a) = 2.3at/2a = 1.15t new displacement is 1/2 (2a)*(1.15t)^2 = 2*1.15^2 at^2 = 5.29*37 = 195.73 m
*September 3, 2014*

**Math/chem**

you gave the formula: 25°C/7min = 25/7 °C/min
*September 3, 2014*

**mathematics1**

exposition is murky, but the result is correct.
*September 3, 2014*

**Math**

Well, is 11 between 30 and 40?
*September 3, 2014*

**calculus**

If this is a typical problem, then if he lands at a distance x from A, then the distance on water is √(x^2+5^2) and the distance on land is 6-x So, the time taken is t = √(x^2+25)/2 + (6-x)/4 dt/dx = x / 2√(x^2+25) - 1/4 = (2x-√(x^2+25)) / 4√(x^2+...
*September 3, 2014*

**math**

(7+16+20+12+8+18)/6 = ?
*September 3, 2014*

**calculus**

πr^2 h = 1000, so h = 1000/(πr^2) surface area is a = 2πr^2 + 2πrh = 2πr^2 + 2000/r da/dr = 4πr - 2000/r^2 = 4(πr^3 - 500)/r^2 da/dr=0 when r = ∛(500/π) thus, h = 100/∛(250π) Do the other along the same way.
*September 3, 2014*

**math**

#1. P(x) = x^2(x^2-9) = x^2(x-3)(x+3) x-intercepts are clearly 0,-3,3 P(0) = 0 for the y-intercept.
*September 3, 2014*

**math**

I'll do #1. You can try the others. 625 = 5^4, so f(x) = 1/5^x or 5^-x
*September 3, 2014*

**calculus**

As usual, draw a diagram. If x is the distance of the beam from the perpendicular line to the wall, then x/8 = tanθ x = 8tanθ So, dx/dt = 8sec^2θ dθ/dt When θ = π/6 (and that's pi, not pie!!) dx/dt = 8(4/3)(20*2π) = 1280π/3 m/s
*September 3, 2014*

**calculus**

Draw a diagram. d^2 = x^2+6^2 2d dd/dt = 2x dx/dt When d=10, x=8 Now plug in your values.
*September 3, 2014*

**calculus**

this is exactly analogous to your other problem with the revolving spotlight. See what you can do for it. Here, you are solving for dθ/dt instead of dx/dt.
*September 3, 2014*

**Root Words**

well, ambi- means two, so I guess that is more than one. I'd give my right arm to be ambidextrous!
*September 3, 2014*

**Algebra**

2√18 - 5√32 + 7√162 2√9√2 - 5√16√2 + 7√81√2 I think you can take it from here, no?
*September 3, 2014*

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