Friday

May 6, 2016
Total # Posts: 40,202

**Math: Parametric Equations**

since sin^2(t)+cos^2(t) = 1, (2+4cos(s))^2 + (3+4sin(s))^2 = 1 See where that gets you.
*April 10, 2016*

**maths**

set up a diagram. You can see that if the angle to the top of the building is a, then x/9 = cot(a) x/16 = cot(a+θ) θ = arctan(x/9) - arctan(x/16) dθ/dx = 0 when x=12 as shown here: https://www.wolframalpha.com/input/?i=arctan%28x%2F9%29+-+arctan%28x%2F16%29
*April 10, 2016*

**maths**

tan(A/2)
*April 10, 2016*

**math**

Assuming the usual carelessness with parentheses, I get 4^(x+3) = 32(2^(x+y)) 2^(2(x+3)) = 2^5*2^(x+y) 2x+6 = 5+x+y x = y-1 9^(y-1) + 3^y = 10 3^(2y-2) + 3^y = 10 3^(2y)/9 + 3^y = 10 3^(2y) + 9*3^y - 90 = 0 (3^y + 15)(3^y - 6) = 0 3^y = 6 y = log6/log3 x = y-1 That answer is ...
*April 10, 2016*

**maths**

logy/log2 = log_2(y) logy/log4 = log_4(y) since 2^2 = 4, log_2(y) = 2log_4(y) = log_4(y^2) so, now we have log_4(y^2*y) = 6 log_4(y^3) = 6 y^3 = 4^6 y = 4^2 = 16
*April 10, 2016*

**math**

2lg5 = lg(5^2) lg[(x+14)/(x-2)] = lg25 (x+14)/(x-2) = 25 x+14 = 25x-50 24x = 64 x = 8/3
*April 10, 2016*

**geometry (check answers)**

a no b many c many d one e no f no
*April 10, 2016*

**Calc**

a little check will show that h = A/w - w/4 So, the perimeter is (assuming the triangle is isosceles) p = w+2h+w√2 = w(1+√2) + 2(A/w - w/4) = (1/2 + √2)w + 2A/w dp/dw = (1/2 + √2) - 2A/w^2 dp/dw = 0 when w = 2√(A/(2+√2)) h = (1+√2)/2...
*April 9, 2016*

**LOGARITHM**

Assuming you meant the log of (2x-1)^2, then that means (2x-1)^2 = e^7 2x-1 = e^3.5 = 33.115 2x = 34.115 x = 17.0577 Looks ok to me. of course, there is the other root using 2x-1 = -33.115
*April 9, 2016*

**Math: Parametric Equations**

cos(4t) has period pi/2 sin(6t) has period pi/3 so, you get the entire curve using the interval [0,pi] as indicated by the note next to the graph at the suggested URL.
*April 9, 2016*

**Math**

of course he is right. The actual room is 18 times as big as the drawing. So, any length on the drawing, times 18, is the length in the room. Any length in the room, divided by 18, is the length in the drawing. That's the whole purpose of scale drawings - to represent the ...
*April 9, 2016*

**History**

indeed
*April 9, 2016*

**History**

What powers did Parliament have in the Bill of Rights?
*April 9, 2016*

**Math: Trigonometry**

we want sin(x+n) = cos(x) sin(x)cos(n) + cos(x)sin(n) = cos(x) we need cos(n)=0 and sin(n)=1 This is true only for n = 2k*pi + pi/2 for k=0,1,2,3... that is pi/2, 5pi/2, 9pi/2, ... 100 * 2/pi = 63.6, so the last entry in the list is 61pi/2 = 95.8
*April 8, 2016*

**History**

thanks
*April 8, 2016*

**History**

yes i would like help with the assignment, like good sites onto where i could find information of this or something
*April 8, 2016*

**History **

1. What powers did Parliament have in the Bill of Rights? 2. Why was King James removed from the throne? 3. Do you think the people of England were more in favor of King William and Queen Mary in being the King and Queen than King James II? Why or nor why not? Support your ...
*April 8, 2016*

**Algerba**

sure thing. When you encounter complicated math problems, just take a deep breath and realize that since you only know a few simple rules for working with the stuff, the big mess can always be broken down into simple pieces that you can do easily, using the rules you know.
*April 8, 2016*

**Algerba**

sure. Note that 4-4=0, so that term goes away. Also, 4/2 = 2. Then you have 3r- 4/2 +4r-12+13s+5r+5(9-r)-6r+2(-4)-5(2s)+2(9+3r)+2-3s = 57 remove the parentheses: 3r-2+4r-12+13s+5r+45-5r-6r-8-10s+18+6r+2-3s = 57 Now collect all the r and s stuff, and collect all the constants: ...
*April 8, 2016*

**Algerba**

ah. never mind. After you clear away all the noise, you are left with 7r+43 = 57 7r = 14 r = 2 the value of s does not matter; it can be anything.
*April 8, 2016*

**Algerba**

still, you want r or s?
*April 8, 2016*

**Algerba**

you have two variables, and unmatched parentheses. You want to solve for r or s?
*April 8, 2016*

**Calculus**

works for me. I did the integral directly, using ∫[0,1] 2π(1-y) arccos(y) dy and got the same answer. I like your technique of avoiding the arccos, though.
*April 8, 2016*

**Math**

better look up the inflation rates between then and now.
*April 8, 2016*

**Math 10- Relations & Functions**

y = 4x-8 C(n) = 14n+5 8x+12 = 132 F(6) = 8*6 + 12
*April 8, 2016*

**Math Help!!!**

looks good to me.
*April 8, 2016*

**geometry**

I'd start with this: The circle's equation is (x - a/2)^2 + (y - b/2)^2 = (a^2+b^2)/4 If a chord intersects the x-axis at x=c, then the slope of the chord is (b)/(a-c) so, the equation of the chord is y = b/(a-c) (x-c) and the length of the chord is 2sqrt((a-c)^2 + b^2...
*April 8, 2016*

**Algebra**

√363 - 3√27 = √(121*3) - 3√(9*3) = 11√3 - 3*3√3 = 2√3
*April 8, 2016*

**Algebra 1**

n = n^1 so, adding exponents, n^-4•n = n^-4 • n^1 = n^(-4+1) = n^-3 or, since n^-4 = 1/n^4, 1/n^4 • n = n/n^4 = 1/n^3
*April 8, 2016*

**mathematics**

all sides are 10, so its base is 10. 10h = 84 h = 84/10 = 42/5
*April 8, 2016*

**Math**

well, what is 100% of 25? Naturally, that's 25, since 100% is all of something. 500% is 5 times 100%, so that is just 5*25 = 125 a little thought can help a lot while you're waiting, rather than whining about it.
*April 7, 2016*

**Mathematics**

yes. the angle is 1/5 of 360°, or 72° and that's rotational symmetry, not system.
*April 7, 2016*

**math**

4.1x10^5 = 4.1 x 100,000 = 410,000
*April 7, 2016*

**Math**

10*9*8 = 720
*April 7, 2016*

**Algebra**

-7 < y <= 3
*April 7, 2016*

**Math**

1/5 + 1/4 = 9/20 so, the rest is 11/20 11/20 x = 11 so, 1/20 x = 1 x = 20 1/5 of 20 is 4 to her brother
*April 7, 2016*

**calc 2**

for our function, y' = 6k(kx)^5 so, we want other curves whose slope is y' = -1/(6k^6) x^-5 y = 1/(24k^6 x^4) or, to make things look more similar, y = 1/(24k^2) (kx)^-4
*April 7, 2016*

**Newtons Second Law**

Net force is 7500-2200-5000 = 300N F = ma, so a = 300N/1200kg = 0.25 m/s^2 the actual speed of the car does not matter.
*April 7, 2016*

**Algebra**

The fill rate is clearly 825 ft^3/hr At 10 hours, that will be 8250 ft^3. no idea of the percent filled. How big is the silo?
*April 7, 2016*

**pre ap math**

cool!
*April 7, 2016*

**Math**

factor out the 9: 9(y^2-9) difference of squares: 9(y-3)(y+3)
*April 7, 2016*

**Algebra**

If there were x oz of almonds, then the rest (300-x) was tea. 0.95x + 2.15(300-x) = 1.85(300)
*April 7, 2016*

**Math**

3 yds = 108 in. So, length+width = 54 in. Starting with w=6, we thus have dimensions of 6,48 7,47 ... 12,42
*April 7, 2016*

**Algebra**

looks good to me.
*April 7, 2016*

**Algebra**

1/5 + 1/12 = 1/x
*April 7, 2016*

**chemistry**

66s is 6 half-lives, so 49.0 * (1/2)^6 = 0.765 μg
*April 7, 2016*

**Chemistry**

80(1/2)^t = 10 (1/2)^t = 1/8 t = 3 so, 45 days is 3 half-lives
*April 7, 2016*

**Algebra**

since time = distance/speed, 132/(x+11) = 132/x - 2 x = 22 6 hrs at 22 mph 4 hrs at 33 mph
*April 7, 2016*

**Algebra**

If it takes A x days, it takes B 2x days. 1/x + 1/(2x) = 1/5 3/(2x) = 1/5 x = 15/2 So, it takes B 15/2 days, and A 15/4 days
*April 7, 2016*

**Algebra II**

so, 8=4p p=2 that is the distance from the vertex to the focus. All you need to do is (a) read what we gave you (b) think about it a bit
*April 7, 2016*

**Algebra II**

for the parabola y^2 = 4px the vertex is at a distance p from the focus.
*April 7, 2016*

**Math**

which are the right angles?
*April 7, 2016*

**chemistry**

142km * 1gal/27mi * .6214mi/km * 3,78L/gal = 12.35L
*April 7, 2016*

**Algebra**

If x at 2 pts, then 24-x at 3 pts. So, adding up all the points, 2x + 3(24-x) = 53 x = 19 for 2-pts so, 24-x = 5 for 3-pts
*April 7, 2016*

**math**

In QI, x>0 and y>0 so, where are x<0 and y<0 ?
*April 7, 2016*

**Chemistry**

What is the mole fraction of NaBr in an aqueous solution that contains 20.1% NaBr (weight/weight%)?
*April 7, 2016*

**Geometry**

For a pentagon with radius r, the apothem is a = r cos 36° = 0.8090r So, the radius of B is .8090 the radius of A. So, B's area is .8090^2 the area of A. So, A's area is 1.53 times the area of B.
*April 7, 2016*

**Algebra**

on the left, you have 4x+2 so on the right, if you have 4x + ? where ? is anything but 2, there can be no solution.
*April 7, 2016*

**Algebra**

translations and reflections do not change distances. So, F'G' is the same length as FG.
*April 7, 2016*

**Algebra**

well, since the grade does not always increase or decrease, it cannot be linear. So, A and B are out. Now look at the data and pick C or D.
*April 7, 2016*

**Math**

clearly the last digit must be 0 or 5 The 1st digit cannot be zero. So, there are 1st digit 5: 1*4*3*1 = 12 last digit 5: 4*4*3*1 = 48 last digit 0: 4*4*3*1 = 48
*April 7, 2016*

**Mathematics**

17+20-32 = 5
*April 7, 2016*

**Math**

If x bought 2 shirts and y bought only 1, then x = 120 9(2x+y) = 5(2x+y+120) + 1288 y = 232
*April 7, 2016*

**calculus**

a = (70-15)/15 = 11/3 km/hr/s Convert that to m/s^2, and then use s(t) = 15km/hr * 15s + 11/6 km/hr/s * 15s^2 = 15km/hr * 15/3600 hr + 11/6 km/hr/s * 15s * 15/3600 hr = 225/3600 + 11/6 * 225/3600 km = 17/96 km or 177 m Don't like mixing up all those units? 15km/hr = 4.167 ...
*April 7, 2016*

**calculus**

a(t) = -32 v(t) = 79 - 32t h(t) = 4 + 79t - 16t^2 Now just find the vertex of that parabola, at t = 79/32
*April 7, 2016*

**Calculus**

If each square has side x, then x = √200, and the total fence is 7√200 m I feel that the two areas are in fact not squares, but rectangles. In that case, if each rectangle has dimensions x by y, and they are separated by a side of length x, then the total fence is ...
*April 7, 2016*

**Math**

it's the same as just placing 3 balls in a row. 6P3
*April 7, 2016*

**math**

(2sinA+1)/(cosA+sin2A) = (2sinA+1)/(cosA+2sinAcosA) = (2sinA+1)/[cosA(1+2sinA)] = 1/cosA = secA
*April 6, 2016*

**Math**

no idea how to parse that. try writing things like 5c^3 or (5c^-3)/(y^4) using one line instead of all those lines.
*April 6, 2016*

**Math**

Since f is only defined on [-8,4] g(x) is only defined on [4,-2]=[-2,4] That is, g(-2) = f(4) and if you try to evaluate g(-3) = f(6) that is not defined. Play around a bit and you'll see that the domain of g is that of f, divided by -2.
*April 6, 2016*

**math**

the ball is at the top of the building to start with. At t=0, the ball is kicked. So, the last term, 146, is the height of the building.
*April 6, 2016*

**math**

well, what is h when t=0?
*April 6, 2016*

**Algebra**

12s+4c = 15 4s+12c = 21 now just solve for s and c.
*April 6, 2016*

**Algebra**

base * height = 96
*April 6, 2016*

**Math**

well i found it, i guess its 456=24t+264, as it gives t=8
*April 6, 2016*

**Math**

p=24t+264? is that right?
*April 6, 2016*

**Math**

Ty is reading a book that is 456 pages. In the last 11 days, he has read 264 pages. If Ty continues to read at the same rate, write an equation that represents the relationship between the number of pages, p, Ty reads over time, t.
*April 6, 2016*

**Geometry**

think about it. The original area is 1/2 bh The new area is 1/2 (3b)(h/3) = 1/2 bh no change.
*April 6, 2016*

**Math/Stats**

enter your data at http://davidmlane.com/hyperstat/z_table.html play around there for a while and it all becomes clearer.
*April 6, 2016*

**maths polynomial help!!!!**

x^2+2x+1 is (x+1)^2 So, do a synthetic division twice by x+1 and you get remainders of c-b and c-2b-a Both those remainders must be zero, so b=c and a+b=0 So, a can be anything, and b=c = -a and you have ax^3 + ax^2 - ax - a = a(x^3+x^2-x-1) = a(x+1)^2 (x-1)
*April 6, 2016*

**Math**

your answer is right, but you should have divided by 9. 5lb * 16oz/lb * 1apple/9oz = 8.8 apple make sure the units cancel correctly
*April 6, 2016*

**math**

4 2/3 + 3 1/3 = 8 oz Now, 40 = 8*5, so he needs 5 times as much of the paints.
*April 6, 2016*

**Algebra II**

#1 c #2 38400/32000 = 1.2 46080/38400 = 1.2 55296/46080 = 1.2 so, in 2015 it will be 55296* 1.2^9
*April 6, 2016*

**Algebra II**

#1,2 - just plug in a value for n #3 Tn = -62 + 15(n-1) = -77+15n #4 Tn = 1/243 * 3^n
*April 6, 2016*

**math**

depends on the wheel's radius. s = rθ all you have said is that s=10.
*April 6, 2016*

**Algebra**

from A to B at speed s took h hours. s*h = 400 on the way back, s*2 + (s+10)(h-2 - 1/3) = 400 h=5, so A to B took 5 hours. so, ...
*April 6, 2016*

**Math**

#1 D assuming the translation moves the 1st point to the 2nd. #2 ok #3 Having gotten #2 right, how can you choose what you did here?
*April 6, 2016*

**Math**

looks good
*April 6, 2016*

**maths**

see http://www.jiskha.com/display.cgi?id=1459708965
*April 6, 2016*

**math**

#1 just plug in various values for n. #2 note that as x increases by 2, y decreases by 1. So, you'd expect something like y = -1/2 x But, -1/2 * 2 = -1, and y = 1, so adjust the rule to be y = -1/2 x + 2 #3 just multiply 159 by the number of seconds.
*April 6, 2016*

**Math**

red = 4 green = 1/4 * 4 = 1 blue = 6*1 = 6 total: 4+1+6 = 11
*April 5, 2016*

**Math**

gotta know how many windows and their size.
*April 5, 2016*

**math**

the money is divided into two parts, in the ratio 12:10 So, 12x+20x = 9152 x = 416 So, Dande gets 12*416=4992 Mani gets 10*416 = 4160 total: 9152
*April 5, 2016*

**Calculus**

sounds like you want f'(x) = x e^(.01x) since you say that's the growth rate. So, the total number of computers for 20 years is the integral from 0 to 20 of f'(x) dx To do the integral, use integration by parts.
*April 5, 2016*

**math**

32°33' - 10°54' = 31°93' - 10°54' = 21°39'
*April 5, 2016*

**math**

and did someone say it was?
*April 5, 2016*

**math**

what, no calculator? Hint: 25^2 = 625
*April 5, 2016*

**math**

(3/8 * 1/4) / (3/4 + 1/5) = (3/32) / (19/20) = 60/608 = 15/152 As written, using PEMDAS and treating the fractions as single units, 3/8 * 1/4 / 3/4 + 1/5 = 3/32 / 3/4 + 1/5 = 1/8 + 1/5 = 9/40
*April 5, 2016*