Monday

January 23, 2017
Total # Posts: 47,949

**history**

This is my last question Describe some of the achievements of the Middle Kingdom of ancient Egypt.

*November 27, 2016*

**history**

What does Herodotus question about the Nile in this quote? why it has its great floods why it has no breezes blowing from it why it has its towering forests why it has its enormous length I need help bad plz. I have tried looking in my text book and everything.

*November 27, 2016*

**history**

Ms. sue I am so dumb SHOuld've read it lol

*November 27, 2016*

**history**

What lands beside Egypt does the Nile flood? Mesopotamia Ethiopia Libya and Arabia Narmer

*November 27, 2016*

**runways and inverses!**

looks good to me.

*November 27, 2016*

**dp**

recall the definition of pressure = force/area

*November 27, 2016*

**Algebra**

n = 2d+1 now add up the values, and then solve for n and d.

*November 27, 2016*

**Math**

treat these just like any other binomial, keeping reals and imaginaries separate: -i-2-(6-4i)-(5-2i) -i-2-6+4i-5+2i (-2-6-5)+(-1+4+2)i -13+5i

*November 27, 2016*

**math**

If the number of seats for the categories is x,y,z then just list the data: x = 9z x = 55+y+z 15x+24y+41z = 46152 Now just solve for x,y,z

*November 27, 2016*

**Algebra**

Since distance = speed * time, 70t + 25 = 60(t + 1/2) t = 1/2 So, 70mi/hr for 1/2 hr = 35mi 60mi/hr for 1 hr = 60mi = 35+25 mi

*November 27, 2016*

**Math algebra**

f^-1 = (x+1)/2 check: f^-1(f) = (f+1)/2 = (2x-1+1)/2 = x f(f^-1) = 2f^-1 - 1 = 2(x+1)/2 - 1 = x

*November 27, 2016*

**Math**

total students: 545 Now, a whole circle is 360°, so 190/545 * 360 = 125.5° and similarly for the other angles.

*November 27, 2016*

**pre calculus**

i = 1 cis ?/2 ?i = ?1 cis ?/8 this is very straightforward, a direct application of the formula.

*November 27, 2016*

**precalculus**

r^2 = x^2+y^2 tan? = y/x same as with polar coordinates.

*November 27, 2016*

**Math algebra**

d = ks^2 So, d/s^2 = k, a constant. So, you want d such that d/56^2 = 60/40^2

*November 27, 2016*

**Math algebra**

A = k*R1*R2/L^2 "exponents" at the bottom are called subscripts.

*November 27, 2016*

**precalcalculus**

if given two angles, use A+B+C=180° Then, if only one side, use law of sines If three sides, use law of cosines to find an angle. If only one angle, use law of sines to get a 2nd one. Then see step 1.

*November 27, 2016*

**Maths, multiplicative inverse**

-3 = 23 (mod 26) 17*23 = 26*15 + 1

*November 27, 2016*

**Math**

6yd * 4yd = 24 yd^2

*November 27, 2016*

**Math**

convert each vector to x-y form add the components convert back to polar

*November 27, 2016*

**Math**

48 is 2 less than 50 50-x is x less than 50 thrice a number less than fifty is 50-3x 7 less than a number is x-7

*November 27, 2016*

**Maths**

the turning points are in between the x-intercepts.

*November 27, 2016*

**Trigonometry**

arctan(cot(x)) = arctan(tan(pi/2-x)) = pi/2-x This is not quite true when dealing with QIII angles...

*November 27, 2016*

**math**

x = kuv/(u+v) when you come up with a question, this should help answer it.

*November 27, 2016*

**math**

D = ks

*November 27, 2016*

**math**

the linear scale is 1:5 so, the areas are in the ratio 1:25

*November 27, 2016*

**Maths**

same as angle D

*November 26, 2016*

**Calculus**

Consider the triangle at distance x. Its base is 2y, and its height is y?3. So, adding up the volumes of all those triangles of thickness dx, we have (applying symmetry) v = 2?[0,3] 1/2 * 2y * y?3 dx = 2?3 ?[0,3] y^2 dx = 2?3 ?[0,3] (9-x^2) dx = 36?3

*November 26, 2016*

**Math**

http://www.wolframalpha.com/input/?i=93log(d)%2B65+for+d%3E0 Note that it's just the usual log graph, shifted up and scaled.

*November 26, 2016*

**pre calculus**

(x^2-25?i)(x^2+25?i) (x-5?i)(x+5?i)(x-5?i i)(x+5?i i) Now just use de Moivre's formulas to find ?i. If you want, you can rephrase these solutions as ±5(-1)^(1/8) ±5(-1)^(5/8)

*November 26, 2016*

**Calculus**

using cylinders, we have v = ?[1,3] 2?rh dy where r=5-y and h=x=(y-1)^2 ?[1,3] 2?(5-y)(y-1)^2 dy = 40?/3

*November 26, 2016*

**Calculus**

draw the region. Using discs (washers), the volume is v = ?[0,4] ?(R^2-r^2) dx where R = 5-y and r = 5-3=2 v = ?[0,4] ?((5-(1+?x))^2-(2)^2) dx = 40?/3

*November 26, 2016*

**calculus**

at time t hours, the distance z is z^2 = (40-20t)^2 + (30t)^2 now just find when dz/dt = 0

*November 26, 2016*

**precalculus**

w = <4,1> - <-8,12> = <12,13> now just convert to polar form.

*November 26, 2016*

**Math**

2/3 = 8/12 so, if he ate 6/12, ...

*November 26, 2016*

**Math**

assuming the house is clean when Mimi gets home, consider that in one hour, 1/5 - 1/7 = 2/35 of the house gets messed up each hour.

*November 26, 2016*

**Math**

Assuming typos, 1/3 of the fish found in February were tagged. So, 180 represents 1/3 of the fish in the lake.

*November 26, 2016*

**Algebra 2**

Bzzt. But thanks for playing... two imaginary solutions means the discriminant is negative: 36-4c < 0 c > 9

*November 26, 2016*

**Algebra 2**

9 = 3^2, so it's (b) which you could have verified by actually doing the multiplication, guy.

*November 26, 2016*

**pre calculus**

these are all the same. You must have some of your own work to show by now.

*November 26, 2016*

**pre calculus**

w = <4,1> - <-8,-12> = <12,13> Now just convert back to polar form.

*November 26, 2016*

**pre calculus**

pick any angle (say, A) and find it via a^2 = b^2 + c^2 - 2bc cosA Now the area is given by 1/2 bc sinA

*November 26, 2016*

**physics**

so, what is the formula for centripetal acceleration? Just plug in your numbers to find ?.

*November 26, 2016*

**Math**

Since the degrees have equal size, (29-21)/(21+273.15) * 100 = 2.7%

*November 26, 2016*

**math**

20% of the sum of their original prices, because of the distributive property.

*November 26, 2016*

**pre calculus**

try getting the notation right: e^(a+bi) = e^a (cosb + i sinb) Now just plug in a=0, b=?

*November 26, 2016*

**calculus**

just integrate each component. 0 to 1800 seconds.

*November 26, 2016*

**Differential calculus**

since h = (10/4) r, v = pi/3 r^2 (10/4 r) = 5pi/6 r^3 now differentiate and solve for dr/dt

*November 26, 2016*

**Calculus**

dz/dy = x e^(xy) + 2cos(xy-1) - 2xy sin(xy-1)

*November 26, 2016*

**Differential calculus**

x^2+y^2 = 20^2 now take derivatives and solve for dx/dt

*November 26, 2016*

**Calculus**

df/dx = e^-x (x^2-2x+y^2) df/dy = 2e^-x y both are zero only at (0,0)

*November 26, 2016*

**Differential calculus**

using similar triangles, when the man is x feet from the building, s/30 = 6/(30-x) 1/30 ds/dt = -6/(30-x)^2 dx/dt Now just plug in your numbers to find ds/dt

*November 26, 2016*

**Differential calculus**

see related questions below

*November 26, 2016*

**Physics**

1*sin30 = 2*sin? as for density, review what refractive index means.

*November 26, 2016*

**Science**

mass = volume*density

*November 26, 2016*

**math**

how many ways to pick a skirt? For each skirt, how many ways to pick a shirt? and so on. Just multiply it all together.

*November 26, 2016*

**maths**

(11+x)(8+x) = 208 x^2 + 19x + 88 = 208 x^2 + 19x - 120 = 0 (x+24)(x-5) = 0 In 5 years they will be 13 and 16 check: 13*16 = 208

*November 26, 2016*

**math**

If the 3rd number is x, then 2x + 2x+1 + x = 33

*November 26, 2016*

**Math**

clearly 4+10 ? 40 (though, 4*10=40) x-6 + x = 40 x = 17 17+23 = 40

*November 26, 2016*

**Math**

not sure what the Arabic says, but log 1/32 = -log32

*November 26, 2016*

**hdhs**

(10+.1)(9+.1)(2.5+.1) - 10*9*2.5 = 13.966 cm^3

*November 26, 2016*

**Calculus**

x ln(1-2y) = z sin((x^2)z)-3y+z x (-2/(1-2y)) = z' sin((x^2)z) + z cos((x^2)z)(x^2 z') - 3 + z' z' = (2x/(2y-1) + 3) ------------------------------------- sin((x^2)z) + x^2z cos((x^2)z) + 1

*November 26, 2016*

**Trigonometry**

I suggest you post the problem exactly as it was given to you. If it's just part of an exercise set, include the instructions that preceded the section containing the problem.

*November 25, 2016*

**Physics**

2.3 kg? That's some pencil!! You sure you did not mean 2.3 g? That's too light. You sure you meant pencil?

*November 25, 2016*

**Trigonometry**

huh? This is a single function! Not sure what you're getting at...

*November 25, 2016*

**Physics**

PE = mgh

*November 25, 2016*

**Electronics**

10 motivated capacitor you mean microfarad? check out the RC constant definition.

*November 25, 2016*

**maths**

since y = rsin? x = rcos? tan? = y/x = ?3

*November 25, 2016*

**Math**

31+32, 20+21+22, ... start near 63/n for the sum of n consecutive integers.

*November 25, 2016*

**Calculus**

a = 1/2 bh da/dt = 1/2 (h db/dt + b dh/dt) Now just plug in your numbers.

*November 25, 2016*

**Maths of class 9**

They have the same base and the same height, right?

*November 25, 2016*

**Math**

Let n=19. Then we have a1+a19 = a1+a1+18d = 2(a1+9d) = 2a10 b1+b19 = 2b10 Now, using the sum ratio, (a1+a19)/(b1+b19) = a10/b10 = (2*19+1)/(2*19-1) = 39/37

*November 25, 2016*

**math**

you know what y = x^2 looks like, right? This one is y = (x-4)^2 so it's the same parabola, just shifted right by 4.

*November 25, 2016*

**math**

note that 4 and 25 are both perfect squares, so I'd try first: (2x+5)^2 bingo!

*November 25, 2016*

**Math**

1/2 - 1/3 = 3/6 - 2/6 = ...

*November 25, 2016*

**Analytic Geometry**

recall that the circle with center at (h,k) and radius r is (x-h)^2 + (y-k)^2 = r^2 just use your numbers ... and review your text material ...

*November 25, 2016*

**maths**

plane: h/2000 = tan 5.2° for the other, fix the typos, draw a diagram and use the law of cosines/sines.

*November 25, 2016*

**Science**

recall that impulse = force * time

*November 25, 2016*

**Math**

2*0.9 + y*0.6

*November 25, 2016*

**Physics, Class XI**

F = ma find a. Then v = at and use t=8.

*November 25, 2016*

**Maths**

every 24 hours it will be 9am again 2003/24 = 83 days + 11 hours so, if it's 9am now, what will it be in 11 hours?

*November 25, 2016*

**sta**

depends on what the passing grade is. You can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html

*November 25, 2016*

**math 113**

its height is zero when it hits the ground, right? So, just solve 1+4t-5t^2 = 0

*November 25, 2016*

**Physics**

Assuming that 30°NE means 30° north of east, then you have <50,0> + <30cos30°,30sin30°> Now just add them up.

*November 25, 2016*

**bms 100**

This is just an arithmetic sequence, with (in thousands) a = ? T10 = 9 S10 = 65 10/2 (a+9) = 65 a = 4 So, the initial salary was 4000.

*November 25, 2016*

**Calculus**

y = secx - tanx y' = secx(tanx-secx) y' = 0 when secx=0 -- never tanx-secx=0 secx(sinx-1) = 0 secx=0 -- never sinx=1 -- x = pi/2 Now, we want x=pi/2 to be a solution, but unfortunately, neither secx nor tanx is defined there. There are no min/max points on the graph of...

*November 24, 2016*

**Phisics**

a = 6/3 = 2 m/s^2 F = ma = 2400N work = force * distance, so figure how far it went in those 3 seconds. Power = Work/time. convert the Watts to hp.

*November 24, 2016*

**Calculus - Optimization**

lots of related questions below

*November 24, 2016*

**Math - Antiderivatives/Integrals**

f'(x) = e^(9x) f(x) = 1/9 e^(9x) + c Now use point P to find c.

*November 24, 2016*

**Math**

Let's say the bowl is a hemisphere. Then, draw a side view. The axis of symmetry of the sphere, and the radius to the edge at the top of the bowl form a right triangle with legs 15cm long. If the right angle is considered to be the vertex angle of an isosceles triangle, ...

*November 24, 2016*

**Math**

18 = 2*3^2 so look at how many times 9 divides 128!

*November 24, 2016*

**Math**

the smaller triangle has an hypotenuse of 6?10 So, the scale ratio is 6?10:24 = ?10:4 That means the areas are in the ratio 10:16 The areas are thus 54 and 86.4

*November 24, 2016*

**math**

just use their definitions: (b) f(x)/g(x) = (3x+2)/(4-5x) (c) f(x)*g(x) = (3x+2)*(4-5x) = -15x^2 + 2x + 8 and similarly for the others.

*November 24, 2016*

**math**

the line y = 1/2 x - 3 passes through (-1,-7/2) 2 = -7/2 + 11/2 so, you want y = (1/2 x - 3) + 11/2 = 1/2 x + 5/2

*November 24, 2016*

**Math**

(1/2):(1/3) = (3/6):(2/6) = 3:2

*November 24, 2016*

**English**

1-6 -- each pair is used, means the same. "far" is an adverb, so you can ask "how far." "A long way" involves a noun, so you cannot attach an adverb "how" to it. This is a very interesting question. The noun phrase is used as an adverb, ...

*November 24, 2016*

**math**

once you have the price for the oranges (let's say, oh, $12.50), then the total selling price for 100 baskets at 30% markup is $12.50 * 1.30 * 100 = $1625.00

*November 24, 2016*

**math**

ok - maybe you can catch my mistake, and answer the 2nd part while you're at it ...

*November 24, 2016*

**math**

If the prices of baskets were x and y, then we are told: 30x+100y = 2450 30*.40x + 100*.30y = 855 so, potatoes cost $40.00 oranges cost $12.50

*November 24, 2016*

**Math**

(7-8*(-1))* -1^2006 = (7-8*(-1)) * -(1^2006) = (7-(-8))* -1 = (7+8) * -1 = -15 However, if you really meant (7-8*(-1)) * (-1)^2006 then the answer is +15

*November 24, 2016*