Friday

November 27, 2015
Total # Posts: 35,819

**math**

you have a point and a slope, so start with that form: y-5 = (2/3)(x+3) Now just rearrange things to wind up with the slope-intercept form. y-5 = (2/3)x + 2 ...
*November 3, 2015*

**Algebra help fast**

correct
*November 3, 2015*

**maths**

so, the 6th term is midway between the 4th and the 8th: 14 I guess that's not what you wanted to know. Note that T8 = T4 + 4d Now you can find d, then a.
*November 3, 2015*

**English 9**

one place to start would be to read some items about surviving in the wilderness, since you seem to have no experience that relates. Then, after thinking about what you have read, write a narrative about how you would use those skills.
*November 3, 2015*

**Mathematics**

draw a diagram. The distance between centers is the sum of the radii, so if the circles have radii a,b,c we have a+b=11 a+c=15 b+c=19 Now it's easy to figure out a,b,c.
*November 3, 2015*

**Mathematics**

use the distance formula and you have PQ^2 = (-2+3)^2 + (3-7)^2 = 17
*November 3, 2015*

**algebra or algebra1**

plot the points. You have an isosceles triangle with base 6 and height 6. Area = 1/2 bh = 18
*November 3, 2015*

**algebra**

If the rates are a and b, then we are told a+b = 175 15a+5b = 1525 Now just solve for a and b.
*November 3, 2015*

**Calculus**

There is no exponential growth here. The population and volume are not growing by a fixed percentage, but just as a linear amount. the concentration is measured in molecules/μm^3, so at t minutes later, c = (10^6 + 10^4t)/(1000+5t) = 2000(100+t)/(200+t) = 2000(1 - 100/(...
*November 3, 2015*

**algebra**

Close. You do need to specify that c is not negative, so the domain is 0 <= c <= 16, or the interval [0,16]. The range would then be [0,1568]. There is no equation, just a couple of expressions.
*November 3, 2015*

**Algebra**

since the perimeter is the sum of the sides, the missing side x must be found using (4z-2)+(3z+2)+x = 112 Now just solve that for x. Since you have not assigned a value to z, the answer for x will still involve z.
*November 3, 2015*

**math**

no way. Different liquids have different weights. A pound of liquid silver will be much smaller than a pound of water.
*November 3, 2015*

**MATH**

2(x+4)(x-2p) = 2(x^2 + (4-2p)x - 8p) Completing the square, we have 2(x + (2-p))^2 - 8p - (2-p)^2) So, at x = p-2, the value is 2(-8p-(2-p)^2) = -2(p+2)^2 If that is -18, (p+2)^2 = 9 p+2 = ±3 p = -5 or 1 check: 2(x+4)(x+10) = 2(x+7)^2 - 18 2(x+4)(x-2) = 2(x+1)^2 - 18 ...
*November 3, 2015*

**MATH**

Find all values of p such that 2(x+4)(x-2p) has a minimum value of -18. (AoPS, Please show steps)
*November 3, 2015*

**Math**

2*75
*November 2, 2015*

**Math**

so, you have (assuming the real world) d = 16t^2, so t = √(d/16) That's how long it takes to fall a distance d. The sound takes another d/1100 seconds to get back. Thus, you have √d/4 + d/1100 = 4 That's just a quadratic equation, so finding √d is easy
*November 2, 2015*

**math**

and the question is ...?
*November 2, 2015*

**Math**

If the single issue price is x, then 29.99/12 = .70x Now just find x, and you can answer part B.
*November 2, 2015*

**Geometry**

looks good to me.
*November 2, 2015*

**Business Calculus**

yes. you know that 2(2l+w)+6w = 600 4l+8w = 600 l+2w = 150 so, l = 150-2w The area is a = lw = (150-2w)w = 150w - 2w^2 So, find w which makes a the maximum. That will be at the vertex of the parabola.
*November 2, 2015*

**math**

The worst case is when all six chairs are sold at the lowest acceptable price, which is 270/6 = $45 each. So, you want w where 80*0.85^w = 45 w = 3.54 So, the 3rd week is the last possible week to make a profit. 80*.85^3 = $49.13 80*.85^4 = $41.76 - too low
*November 2, 2015*

**9th grade**

Fractions are always messy. Since the LCD of 1/3 and 1/4 is 12, try multiplying everything by 12. Then you have 96 = 12b + 16 Now you can find b, right?
*November 2, 2015*

**Math**

that's the way I'd do it. Of course, the reverse ordering would also be a way to do it. Your way gives you the European size for a given US size.
*November 2, 2015*

**bearing**

As always, draw a diagram. The x- and y- components of the distances are PQ:<5cos60°,-5sin60°> QR:<3cos30°,3sin30°> add them up to get PR. The find its magnitude and direction.
*November 2, 2015*

**Algebra**

Draw a diagram. You can see that x^2 = 80^2 + 30^2 assuming he tried to swim straight across. Although the question is worded poorly. He swam 80m, regardless of how far the river took him.
*November 2, 2015*

**math**

odd definition, but try just substituting in for y: y = x/(2x^2-x+8) (x-1+y)^2/4y =(x-1+(x/(2x^2-x+8)))^2/(4(x/(2x^2-x+8))) = (2x^3-3x^2+10x-8)^2 / 4x(2x^2-x+8) (x-1+y)^2/4y=(1+2y-63y^2)/16y^2 =(1+2(x/(2x^2-x+8))-63(x/(2x^2-x+8))^2)/(16(x/(2x^2-x+8))^2) = (x^2-4)^2 / 4x^2 I ...
*November 2, 2015*

**trig**

x = |v| cos 45° y = |v| sin 45° surely you can sketch the vector.
*November 2, 2015*

**trig**

if the wind's vector is w, then u+w = v <487,-780> + <x,y> = <527,-628> So, now you can figure x and y, then get the speed and direction.
*November 2, 2015*

**Math**

3/4 x = 4 2/3 x = (4 2/3)/(3/4) = 14/3 * 4/3 ...
*November 2, 2015*

**Math**

Nothing to solve. If you mean to simplify it, then 4m(-2mn^2)^3 / 4m^-6n4 = 4m(-8m^3n^6) / 4m^-6n^4 = -32m^4n^6 / 4m^-6n^4 = -8m^10n^2
*November 2, 2015*

**math**

a = 2b 2a+3b = 75
*November 2, 2015*

**Math**

That's better
*November 2, 2015*

**physics**

well, since the voltage ratio is the same as the ratio of turns, you would have 120 * 20/200
*November 2, 2015*

**math**

do this one like the earlier problem.
*November 2, 2015*

**math**

since the period is 1/17 sec, then we will have sin/cos (34πt). Since we are starting at the minimum, and cos(x) starts at the maximum, D(t) = -12*0.92^(t) cos(34πt) or, in the more usual form, D(t) = -12 e^(-0.083t) cos(34πt)
*November 2, 2015*

**algebra**

since distance = speed * time, (s-80)(4) = (s+80)(3)
*November 2, 2015*

**Trigonometry**

recall that in a right spherical triangle with sides a,b,c cos c = cos b * cos a so, he have cos c = √3/2 * 1/2 = √3/4 c = 64.34° = 1.123 radians so, since s=rθ, the arc length of c is 5000 * 1.123 = 5615 km
*November 2, 2015*

**math**

Actually, 1A is correct 4A is a correct expression, but not completely factored
*November 2, 2015*

**College Algebra**

I=N/P+c I-c = N/P P = N/(I-c)
*November 2, 2015*

**calculus**

v = x^3 when v=64, x=4 dv/dt = 3x^2 dx/dt now just plug in your numbers. Watch the units.
*November 2, 2015*

**tema senior high school**

If x-cm cuts are made, the base is 100-2x cm, and the height is x cm. The area is thus (100-2x)^2 + 4x(100-2x) = 100^2 x = 2500/(100-2x) - 4(100-2x) The volume is v = x(100-2x)^2 = (2500/(100-2x) - 4(100-2x))(100-2x)^2 Now expand that, take dv/dx=0 and find x for maximum ...
*November 2, 2015*

**Math**

1/10 + 1/2 + 1/4 = 31/40 So, 9/40 x = 45 x = 200 So, 1/4 * 200 = 50 are orange
*November 2, 2015*

**Word Problem**

if w at Westside, then the rest (12-x) are at Pinewood. So, 98w + 115(12-w)
*November 1, 2015*

**Algebra 2**

|2x–1| ≥ -5 is clearly true for all x, since |x| is always positive.
*November 1, 2015*

**math**

−2 ≤ 1 − (2 + 4x) < 3 -3 ≤ -(2+4x) < 2 3 >= 2+4x > -2 1 >= 4x > -4 1/4 > x > -1 See the graph at http://www.wolframalpha.com/input/?i=plot+y%3D+1+%E2%88%92+%282+%2B+4x%29%2C+y+%3D+-2%2C+y%3D3
*November 1, 2015*

**Physics**

F = ma but, friction µ reduces F, meaning that (1-µ)F = ma 0.53F = 5.6*3.12 ...
*November 1, 2015*

**Quantitative Math**

well, it will double 8 times in 40 days, so 3250*2^8
*November 1, 2015*

**algebra**

since the height/shadow ratio is the same 5/3.5 = h/14 or, just note that the pole's shadow id 4 times as long, so the pole is 4 times as tall.
*November 1, 2015*

**Calculus 1**

looks correct. The fence is divided equally among lengths and widths.
*November 1, 2015*

**math**

if the dimensions of the pool are w and 2w, then (w+8)(2w+8) - w(2w) = 136
*November 1, 2015*

**Algorithm**

assuming you have filled in an array (call it days) of 12 elements, each with the number of days in the month, get date (m/d/y) split into month,day,year if day < days[month] then &nbrsp;&nbrsp;day++ else if month < 12 then &nbrsp;&nbrsp;day=1 &nbrsp;&nbrsp;month++ else...
*November 1, 2015*

**Math**

46.9825 - 0.85870x
*November 1, 2015*

**rew**

well, you know that v^2 = 2as so plug in your values for a and s.
*November 1, 2015*

**Abiboss**

it is easy to construct an equilateral triangle, giving you a 60° angle. Now you can double that and halve that for the two angles you want. That should get you started.
*November 1, 2015*

**MATH**

If I read your notation right, you have -3x/√3 54x^4 + 2/√3 16x^7 Seems kind of odd, so maybe it's wrong. But whatever, is there a question in here somewhere? Ahh. Maybe you have -3x∛(54x^4) + 2∛(16x^7) note that ∛27x^3 = 3x ∛8x^6 = 2x^2...
*November 1, 2015*

**Algorithm**

why not PROMPT “Please enter n” GET n m=0 WHILE m < n COMPUTE m = m+1 DISPLAY m ENDWHILE
*November 1, 2015*

**Calculus**

Why do you integrate over [-2,2]? The curves intersect at (-2,4) and (2,4) but what does the line x = 1/2 have to do with it? There's a region left of the line, and a region right of the line. Since we are rotating about the y-axis, I think we want the region from x=1/2 to...
*October 31, 2015*

**Calculus**

well, you have the function. The average rate of change is just (change in volume)/(change in radius). So, (i) (V(6)-V(3))/(6-3) (ii) (V(4)-V(3))/(4-3)
*October 31, 2015*

**Algebra**

You just have to find x such that f(x) = 12 2(x+8) = 12 x+8 = 6 x = -2
*October 31, 2015*

**ap physics**

C the horizontal motion does not affect the vertical speed. This is assuming, of course, that the 2nd ball was dropped from a height of 50m. The problem does not say.
*October 31, 2015*

**science**

how do you define the best view?
*October 31, 2015*

**math,fraction**

x*16 + 2 = 10 Now just find x.
*October 31, 2015*

**physics**

clearly the minimum deceleration time is (10m/s) / (5m/s^2) = 2 seconds the distance traveled is thus s(t) = 0.5*10 + 10*2 - 2.5*2^2 = 15m
*October 31, 2015*

**math**

Assuming a 24-hour clock and chime, that would be 24/2 (2+23) If it starts over again with one chime at 1:00, then the sum is 2*12/2(2+11)
*October 31, 2015*

**physics**

well, you know that m1 * d1 = m2 * d2 but don't forget the mass of the seesaw on each side of the fulcrum. You don't say whether or not the fulcrum is in the center, but it usually is for a seesaw. The only remaining question is: what the heck is a season?
*October 31, 2015*

**MATHS**

did you plot the points? Clearly the other two points are C:(4,0) and D:(1,4) So, the trapezium has bases 2 and 8, and height 4. Think you can take it from there?
*October 31, 2015*

**math**

(-0.25x - 3) - (1.5x + 1.4) -0.25x - 3 - 1.5x - 1.4 -1.75x - 4.4
*October 31, 2015*

**Physics**

what is the difference between separation and boundary?
*October 30, 2015*

**Math**

well, either sin4x=0 or cosx=0 so, 4x = 0,pi,2pi,3pi,4pi,... meaning x = n*pi/4 for n=0 to 7 or, x = pi/2 or 3pi/2 but those are already covered by sin4x=0 see http://www.wolframalpha.com/input/?i=+2sin4x+cosx
*October 30, 2015*

**G.G.S.S.**

20 m/s^2 * 1km/1000m * 3600s/hr = 72 km/hr/s So, it will take (72-18)km/hr ---------------------- = 3/4 s 72 km/hr/s or, you can convert km/hr to m/s and do it that way. Still, 3/4 second seems awfully fast braking for a train. Better check my math
*October 30, 2015*

**Maths**

well, try factoring it y = (x-1)((x-1)^2 - 4) = (x-1)(x-1+2)(x-1-2) = (x-1)(x+1)(x-3) That help? Naturally, the y-intercept (at x=0) is at y=3
*October 30, 2015*

**Math**

well, for x <= 25, f(x) = 8.80 + 0.6686x Now what about for x > 25?
*October 30, 2015*

**Math**

Looks good to me.
*October 30, 2015*

**math**

type in your functions here and see all the details. http://calc101.com/webMathematica/long-divide.jsp
*October 30, 2015*

**English**

thank you
*October 30, 2015*

**English**

What is the noun clause in the following sentence? I heard that the book is set to release soon.
*October 30, 2015*

**suncrest high school**

reflection in the x-axis takes (x,y) -> (x,-y) so, just change the signs of all the y-values.
*October 30, 2015*

**Maths**

f(x) maps vales in the domain to values in the range, using the given rule. So, to find f(1/4), replace all the x's with 1/4: f(1/4) = 2(1/4)^2 + 2 Now just simplify that.
*October 30, 2015*

**college physics - incomplete**

No unique solution. 20'@90 + 3h@50 = 30+150 = 180km 1h20'@90 + 2h@50 = 120+100 = 220km 2h20'@90 + 1h@50 = 210+50 = 260km Some info is missing.
*October 30, 2015*

**Pre-Algebra, please help!**

only repeating decimals can be expressed as rational numbers. So, you are correct.
*October 30, 2015*

**Trigonometry**

the scale ratio is 3'/8" so, using that ratio on 10", you have 3'/8" * 10" = 3'*(5/4) = 15/4' = 3'9"
*October 30, 2015*

**algebra 1**

Bzzzt. but thanks for playing.
*October 30, 2015*

**algebra 1**

c is slope-intercept. The point slope form of the line through (h,k) with slope m is y-k = m(x-h) any other choices look like that?
*October 30, 2015*

**math**

well, considering that -1 = -3/3, what about -4, -3, -2,...,13 same thing. Just keep adding 1.
*October 30, 2015*

**Math**

that is 0-√3^2 = -√9 = -3 powers come first, then subtraction.
*October 30, 2015*

**Math**

looks like a G.P. with a = 4√3 r = 1/4 S = a/(1-r) = 16/√3
*October 30, 2015*

**Math**

As usual, draw a diagram. You can easily see that if you are x away from the wall, the angle of elevation of the bottom of the screen (A) is cotA = x/3 A = arccot(x/3) angle B to the top is cotB = x/10 B = arccot(x/10) So, since θ = B-A dθ/dt = dB/dt - dA/dt = -3/(x^...
*October 30, 2015*

**Math**

No, you have found cos^2 (x/2) check your half-angle formulas.
*October 30, 2015*

**Algebra**

The domain is the set of all the 1st elements of the pairs. A is the range.
*October 30, 2015*

**math**

old perimeter is 2(w+2w) so, 2(2*w+ 2w+6) = 2(w+2w)+20 Now you can find w and 2w.
*October 30, 2015*

**Calculus 1**

Sorry. I might be less grumpy if you actually showed some of that hard work. Given the info I provided above, (a) B is increasing where B' > 0, so 2/∛ - 1 > 0 2/∛x > 1 2 > ∛x 8 > x So, B is increasing on (0,8) B is decreasing on (-∞,0...
*October 30, 2015*

**Calculus 1**

why is this causing difficulties? B'(x) = 2/∛x - 1 B'(x) = 0 at x=8 as you will recall, B is increasing where B' > 0 B is concave up where B" > 0
*October 30, 2015*

**Calculus 1**

well, the derivative is 7e^-7x where is that zero?
*October 30, 2015*

**Calculus 1**

well, (e^−x)*(−e^−6x) = -e^-7x as you know exponentials have no local max/min, so the extrema are at the ends of the interval. That should pose no difficulty, if you sketch the graph.
*October 30, 2015*

**Math**

well, just keep track of the signs as you work it out. cos2x = 1 - 2sin^2x = 1 - 2*9/25 = 7/25 Or, if you insist on doing it the hard way, cos2x = cos^2x - sin^2x = 16/25 - 9/25 = 7/25 If you came up with -7/25, you need to remember your simple Algebra I!
*October 30, 2015*

**Math**

well, 6/7 of the population has just the symptoms. So, what's 6/7 of 40?
*October 29, 2015*

**math urgent help needed!!**

see the related questions below.
*October 29, 2015*

**math**

gal * miles/gal = miles so, if you know your gas mileage, just do the math.
*October 29, 2015*

**Math Pre-Algebra**

5.55% = 1/18 so, cut the cake into 18 equal squares. The cake is twice as long as it is wide, so that means cut half the cake (6 3/4 x 6 3/4) into 9 pieces, each with a side of 1/3 * 6 3/4 = 2 1/4 inches.
*October 29, 2015*

**math**

They are the points where the graph crosses the x-axis. That is, where ax^2+bx+c = 0
*October 29, 2015*