Tuesday

October 25, 2016
Total # Posts: 45,262

**Trigonometry**

short answer: no you can always use graphical or numeric methods to find the zeros of the function f(x) = tan(x) - 2 Then there are Taylor Series, etc. Your best bet is just to use a calculator (online or mechanical), just as you would to fine log(12) or e^3.1 or any other ...

*September 19, 2016*

**Trigonometry**

you evidently need to review the definitions of the basic trig functions. In this case, tanθ = 75/100

*September 19, 2016*

**math**

well, just look. They added just one textbook, and the weight grew by 1 kg. Clearly the extra textbook weighed 1 kg. Or, algebraically, 3d+3t=9 3s+2t=8 subtract and you get rid of the d's, leaving 0d+1t = 9-8 t=1

*September 19, 2016*

**Maths**

3*39 = 3^2 * 13 now turn that into a list of all factors

*September 19, 2016*

**maths**

with a little expansion, you can arrive at sin(5x)+sin(7x) = 4sin(x) cos^2(x) (2cos(2x)-1) (2cos(2x)+1) now the roots are easy to find.

*September 19, 2016*

**mathematics help**

unusual to have complex coefficients, but x^2 = -16j = 16cis(3π/2) x = ±4 cis(3π/4) = ±4 (-1/√2 + 1/√2 j) = ±2√2 (-1+j)

*September 19, 2016*

**science**

the mass does not matter. a = (20m/s)/(5s) = (20/5) m/s^2

*September 19, 2016*

**mathematics need help**

since the slope is 3, start with x = t y = 3t since the y-intercept is -2, y = 3t-2

*September 19, 2016*

**calculus help me asap**

Here's what wolframalpha.com ends up with: http://www.wolframalpha.com/input/?i=derivative+y%5E6%3Dtanh%5E-1(tan%5E-4(4x%5E2%2By%5E2)%5E2)%5E9 That's as you typed it. I interpreted it as http://www.wolframalpha.com/input/?i=derivative+y%5E6%3Dtanh%5E-1(tan%5E-4((4x%5E2...

*September 19, 2016*

**calculus help me asap**

this is just stupid. y^6 = tanh^-1(u)^9 6y^5 y' = 9 tanh^-1(u)^8 * 1/(1-u^2) du/dx where u = tan^-4(v^2) and v = 4x^2+y^2 = cot^4(v^2) du/dx = 4 cot^3(v^2) (-csc^2(v^2)) (2v dv/dx) dv/dx = 8x + 2yy' mash all that together and solve for y' I see little to be gained ...

*September 19, 2016*

**Maths**

well, 40 = 5*8 55 = 5*11

*September 19, 2016*

**Maths**

not sure what the :||+|| means and it appears you have too many = signs but yes, 2*2 = 4

*September 19, 2016*

**math**

3d+2t = 8 3d+3t = 9 clearly, t=1

*September 19, 2016*

**Math 115**

for 100 < P, C(P) = 100 + 0.72(P-100) or C(P) = P - 0.28(P-100)

*September 19, 2016*

**Math 115**

for 30 < t <= 40, D(t) = D(30) = 2 for 40 < t <= 65 D(t) = 2 + (1/60)(t-40)

*September 19, 2016*

**math**

60/x = sin30°

*September 19, 2016*

**Math115**

t is in minutes, and D is in miles. Since the speed is given in mi/hr, you have to divide that by 60 to get mi/min

*September 19, 2016*

**Math115**

why all the words? Just say D(t). I'll do the first piece. See what you can do with the rest. Starting from t=0, having gone 0 miles so far, D(t) = 0 + 4/60 (t-0) for 0 <= t <= 30 = 1/15 t That may seem cumbersome, but therein lie hints for the other parts.

*September 19, 2016*

**Algebra**

since the slope m is constant, (13+5)/(3-r) = m You have not included the value of m, but once you divulge that secret, you can find r.

*September 18, 2016*

**math**

since the model is 1/16 as big, just divide all the dimensions by 16: boat: (17/16) ft car: (20/16) ft You might want to express those in inches

*September 18, 2016*

**Math**

x^2 - 2x it's as valid as any other expression.

*September 18, 2016*

**Physics**

v = 9.8t s = 100 - 4.9t^2

*September 18, 2016*

**College Algebra**

why the inconsistency? Either say 4 less than t less than or equal to 6 or, my favorite, 4 < t <= 6 For that piece, we have C(t) = 4 for 4 < t <= 6 see what you can do with the others.

*September 18, 2016*

**Math**

how come you can say + but cannot say - ???? 1/4 + 2/7 + 11/12 - 3/4 = 2/7 + 11/12 - 1/2 = 24/84 + 77/84 - 42/84 = ...

*September 18, 2016*

**Math**

(81+11 - 8*4)*1 = 60

*September 18, 2016*

**math**

355-2 < v < 355+2

*September 18, 2016*

**physics**

without relying on friction, I assume you mean that the cars scrape along the wall, since they cannot grip the road without friction.

*September 18, 2016*

**Math**

total = each * number

*September 18, 2016*

**physics**

just figure total load weight so that it equals the weight of the air displaced.

*September 18, 2016*

**math**

you need to distinguish between asking a question and giving instructions. Question: What is the total number of acres planted? Instructions: Compute the total number of acres planted. Now that the English lesson is done, on with the math ... Just add up the amounts. The LCD ...

*September 18, 2016*

**MathEmatics**

yes why not just write 1/20?

*September 18, 2016*

**Physics**

going across the puddle, s = 20t - 1/2 at^2 = 25 v = 20 - at = 5 solve for a and t.

*September 18, 2016*

**Math**

how many face cards are there? chance of getting 1: ? with one missing, chance of getting another: ? multiply the two.

*September 18, 2016*

**Calculus III**

For P:(x,y,z) distance from P to the x-axis: √(y^2+z^2) distance from P to the yz-plane: x So, √(y^2+z^2) = 4x y^2+z^2 = 16x^2 x^2/1 - y^2/16 - z^2/16 = 0 I'll get back to you on the rest.

*September 18, 2016*

**English**

only #1 is clear and concise. #5 is more explicit, but in a classroom setting, I think #1 implies #5. You certainly don't want to talk about the summary, rather than the passage.

*September 18, 2016*

**Math**

14*2/7-3+9 = 10

*September 18, 2016*

**Math**

it's even easier to see if you call them x-2, x, x+2 what's the sum?

*September 18, 2016*

**Math**

there are 5 choices, but only 1 is a success. So, that means there are 4 wrong choices. The odds are 4:1 against, or 1:4 in favor. The probability of a 5 is 1/5. odds are the ratio of success:failure

*September 18, 2016*

**Math**

3*4 = 12 3*5 = 15 so, ...

*September 18, 2016*

**math**

e^x: 2.718 7.389 20.08 54.598 148.413 403.428 so, it grows faster than e^x as x gets large maybe e^(kx^2) can be adjusted some. Since it is not at all obvious (to me), and since there are only 6 data points, it will be e possible to fit any suitable polynomial or exponential. ...

*September 18, 2016*

**Math 2**

Hmmm. √3 sinx = 2+cosx 3sin^2(x) = 4 + 4cosx + cos^2(x) 3 - 3cos^2x = 4 + 4cosx + cos^2(x) 4cos^2(x) + 4cosx + 1 = 0 (2cosx + 1)^2 = 0 cosx = -1/2 Looks like that is a good starting point. Check for extraneous solutions.

*September 18, 2016*

**math**

I'm sure you can find the area A of a right triangle. The volume of the prism is just V = A*length

*September 18, 2016*

**Math**

the area scales as the square of the ratio, so it will be 800 * (3400/5000)^2

*September 18, 2016*

**Math**

total points: 60*100 top 30: 30*80 Now see how many points you have to divide among the other 70 students.

*September 18, 2016*

**math**

576/9 = 64 So, there were 4*64 muffins 5*64 cookies

*September 18, 2016*

**math**

x + 38b = 2.13 x + (38-26)b = 0.96 now just solve for x.

*September 18, 2016*

**Algebra**

first, find t. I assume these are speed * time calculations. Once you have t, use either expression to find the distance.

*September 18, 2016*

**Maths**

9/30 = 30% which had marks. So, we assume that 60 = 30% of the total.

*September 18, 2016*

**Math**

online we use ^ for powers. So, a^2 + x^2 = 4^2 x^2 = 16-a^2

*September 18, 2016*

**Math**

(x+5)/x = 4/3

*September 18, 2016*

**Algebra2**

thank you

*September 18, 2016*

**Algebra2**

well, it is clear that x = 8-y-z plug that into the other two equations. Then make a final substitution there for y or z.

*September 18, 2016*

**Algebra2**

Solve the system by substitution -x-y-z=-8 -4z+4y+5z=7 2x+2z=4

*September 18, 2016*

**Algebra2**

visit http://www.gregthatcher.com/Mathematics/GaussJordan.aspx for all the details.

*September 18, 2016*

**Algebra2**

Solve the system by elimination. -2x+2y+3z=0 -2x-y+z=-3 2x+3y+3z=5

*September 18, 2016*

**mount ayliff comprehensive high school**

Go west, young man.

*September 18, 2016*

**algebra**

x: side of smaller square x+4: side of larger square (x+4)^2 = 4x^2 - 14

*September 18, 2016*

**math**

3:1 = 540:180

*September 18, 2016*

**Algebra**

see related questions below

*September 18, 2016*

**maths**

50 sin70° time to review the basic trig functions and right triangles. And ships sail on headings, not bearings.

*September 18, 2016*

**mathematical physics**

well, you have M = xy N = x^2y^2 so the integral is just ∫∫R (Nx - My) dx dy Along y=0, dy=0, Along x=1, dx=0, Along y=2x, dy = 2dx Now just break the boundary into three parts, and evaluate each part. Watch the direction of the limits.

*September 18, 2016*

**Maths**

net fill rate: 40L/min so figure the volume filled in 15 min.

*September 18, 2016*

**science**

Try retyping using the characters < <= > >=

*September 18, 2016*

**Maths Exponents**

11 x 10^-5 = 1.1 x 10^-4 The distance would be 1.496E11 - 3.84E8 = 1.496E11 - 0.00348E11 = ...

*September 17, 2016*

**mathematics**

work with the costs for x km: 250+.22x 96+.5x

*September 17, 2016*

**Math**

Online you needed parentheses so things are not ambiguous. You want a common denominator, so note that x^2+x-12 = (x+4)(x-3) x^2-16 = (x+4)(x-4) Now you can see that the LCD is (x+4)(x-4)(x-3) and work with that.

*September 17, 2016*

**Math**

as with all problems of addition of fractions, you want the LCD. In this case, that is 30m. Now add things up the way you always do with fractions.

*September 17, 2016*

**maths need help**

I'll take a stab and say that the road is 1m away from the field. So its inner radius is 41 and its outer radius is 42. So, the cost is rate * area = π(42^2 - 41^2) * 26

*September 17, 2016*

**math**

what are all these broken lines? Just type the numbers you want to use. And if you want to use fractions, just type them normally, as in 3/4, 1/8, etc. I spell copy/paste from some word processor. A big clue is the garbled line feeds and the em-dash minus signs.

*September 17, 2016*

**English**

thank you

*September 17, 2016*

**English**

What type of pronoun is used in the following Sentence Under the most splendid house in the city is still to be found the cellar where they store their roots as of old? a- personal b- reflexive c- indefinaite d- interrogative my answer is a

*September 17, 2016*

**Advanced Functions 12**

You need f(f^-1(x)) = x -√(x^2-2 + 2) = -√(x^2) = -x this fails because x^2 is not one-to-one

*September 17, 2016*

**PRE-CAL**

can't see the table, but you have correctly solved for t.

*September 17, 2016*

**Math**

so, what are you trying? Apparently you have done some work, so show us how far you got. It's probably just something simple.

*September 17, 2016*

**math**

since e+e = e e=0 now pick any h&m that add to less than 10

*September 17, 2016*

**algebra**

Fix your typo. You have two "=" signs Your choices are garbled, as well.

*September 17, 2016*

**Business maths**

if the cost is c and the marked price is p, then .70 * p = 1.25c = c+91 .25c = 91 c = 364 p = 1.25*364/.7 = 650

*September 17, 2016*

**Math**

using the quadratic formula, we have x = [-(k+2)±√((k+2)^2 + 12k)]/2k For the roots to be real, we need (k+2)^2 + 12k >= 0 -8-√60 <= k <= -8+√60 Now, we want the roots to be positive, so we need [-(k+2)±√((k+2)^2 + 12k)]/2k > 0

*September 17, 2016*

**math**

π*45^2*130 --------------- 1.2445

*September 17, 2016*

**Math**

rice: 11/18 (7/18 left) tomatoes: (3/7)(7/18) = 3/18 (4/18 left) spinach: (1/4)(4/18) = 1/18 (3/18 left) ...

*September 17, 2016*

**maths**

ok. that was fun.

*September 17, 2016*

**Maths**

.3x + 20 = .8x

*September 17, 2016*

**College Algebra**

your functions are correct. You need to find out what syntax the software expects. Maybe you could try using fractions: D(t) = t/20 0<=t<=25 5/4 25<t<=40 5/4 + t/60 40<t<=70 or maybe the x's confused it.

*September 17, 2016*

**Maths**

try figuring how many do contain a five? Then subtract that from the number of 3-digit values.

*September 17, 2016*

**maths**

eh? eh? try using some parentheses, as you can see that the online formatting is poor. At least some spaces, to indicate breaks. And are those exponents, as in m^3 = m cubed

*September 17, 2016*

**algebra**

(3 ozAg) * (1 ozAu)/(s oz Ag) * $d/(10 ozAu) = $(3d / 10s)

*September 17, 2016*

**Math**

correct

*September 16, 2016*

**Math**

$3.60 * (2/6) = $1.20

*September 16, 2016*

**algebra**

w(w+4) = 7w+18

*September 16, 2016*

**Algebra**

4*86 <= 84+84+88+x <= 4*90

*September 16, 2016*

**Advanced Functions 122**

for every integer k, x = k*360°, y is undefined.

*September 16, 2016*

**Advanced Functions 12**

if I decipher the question correctly, the answer is no. y = x^3 + 4 has odd end behavior, but is not an odd function.

*September 16, 2016*

**linear programming**

or visit http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html and it will show you how it's done

*September 16, 2016*

**partial maths**

wolframalpha.com can verify your answer. http://www.wolframalpha.com/input/?i=partial+fractions+x%5E3%2F(5x%5E3-1) This one is kinda nasty, since 5x^3-1 does factor, but not with integer coefficients. It's a difference of two cubes, so it factors as (∛5 x - 1)(∛...

*September 16, 2016*

**statistics**

total points: 10*24 = 240 after removal of 42, you have 9 scores with a total of 198. So, ...

*September 16, 2016*

**maths helpppppp me asap plz**

∑1/n diverges, so there is no LUB

*September 16, 2016*

**math**

Come on - this one is easy. You have z+7+5 ends in 4 7+5=12, so z=2 Now work with that same idea to get x. Remember that no one said that x,y,z had to be different from all the other digits already present.

*September 16, 2016*

**calculus plz help me**

r = (1+y'^2)^(3/2) / |y"| y^2 = 4ax, so y = 2√(ax) y' = a/√(ax) y" = -a^2/(2(ax)^(3/2)) = -a/(2x√(ax)) so just plug it in: (1+y'^2) = 1+a/x r = ((a+x)/x)^3/2 * 2x√(ax)/a = 2(a+x)^(3/2) / √a

*September 16, 2016*

**algebra - incomplete**

I guess that would depend on the size of the lids, eh?

*September 16, 2016*

**College Algebra**

1/4 of a complete circle, so π/2 (16^2 - 12^2) in^2 that's assuming that the blade extends to the end of the wiper arm. how do you now what automobiles suppose?

*September 16, 2016*