Thursday

May 28, 2015

May 28, 2015

Total # Posts: 31,427

**Trigonometry (identities)**

sin(α+β)+sin(α-β) = sinα cosβ + cosα sinβ - (sinα cosβ - cosα sinβ) = 2cosα sinβ I suspect a typo. I will use (-8cosxsinx+4cos2x)^2 + (4cos2x+8sinxcosx)^2 = (-4sin2x+4cos2x)^2 + (4cos2x+4sin2x) = 4^2((cos2x-...
*March 31, 2015*

**Math**

if you say so.
*March 31, 2015*

**MATH**

716-{(1950/5 of 3)-(4+217/7)} of just means times, so you have 716-{(1950/5 * 3)-(4+217/7)} 716-{(390*3)-(4+31)} 716-{1170-35} 716-1135 -419
*March 31, 2015*

**physics**

(9.6*10^-6 * 6.24*10^18)/(29*4*10^23) = ?
*March 31, 2015*

**Maths**

1 - (4/9 + (2/5)(5/9)) = 1/3
*March 31, 2015*

**Maths**

2/5 rotten means 3/5 fresh 3/5 * 5/8 = 3/8 kg
*March 31, 2015*

**This is nothing to do with school**

3a+c = 30 a+3c = 22 take it from there...
*March 31, 2015*

**ABC**

drop the stone and time how long it takes to hit the ground. Actually, that does not measure the height of the building. He infers the height from the time taken. To actually measure the height, he'd probably have to measure the width of the stone and then count how many ...
*March 31, 2015*

**science**

Vx = 9.8 Vy = √(2as) = √(2*9.8*100) = 44.27 final v = √(Vx^2 + Vy^2)
*March 31, 2015*

**calculus**

cos2x = secx 2cos^2(x)-1 = 1/cosx 2cos^3(x) - cosx - 1 = 0 you will probably need to use a graphical or numeric method to solve this. However, you know that cos2x never gets more than 1, and secx never gets less than 1. So, you will need cos2x = secx = 1 or cos2x = secx = -1 ...
*March 31, 2015*

**Algebra**

(a) look good (b) the friend
*March 31, 2015*

**algebra**

since x is proportional to y, x = ky That is, x/y is constant. So, 12/16 = 1/y
*March 31, 2015*

**chemistry**

well, PV = nRT plug in your numbers and solve for P.
*March 30, 2015*

**Calculus**

profit = revenue-cost revenue = 20*4πr^2 = 80πr^2 cost = 800*4/3 πr^3 = 3200/3 πr^3 so, profit = 80πr^2 - 3200/3 πr^3 max profit when 160πr - 3200πr^2 = 0 160πr(1-20r) = 0 r = 1/20 ft looks like marbles make the most money.
*March 30, 2015*

**math**

24*72 = 24*3*24 = 3*24^2 so, its root is 24*root(3)
*March 30, 2015*

**5th grade (math)**

no idea. How big is the lawn?
*March 30, 2015*

**English**

my answer is B
*March 30, 2015*

**English**

Which of the following moments in "The Most dangerous Game" represents an example of foreshadowing? a-Whitney & Rainsford';s discussion about hunting b- Rainsford's observing the gate of the chateau c- Whitney's comment about the light of Rio?
*March 30, 2015*

**math**

see some of the related questions below.
*March 30, 2015*

**math - eh?**

How did Kayla give away 3/2 beads? Try posting the question as you received it.
*March 30, 2015*

**Calc.**

I must be missing something. Clearly the minimum length of fold is achieved when the paper is folded in half, so the upper right corner touches the lower right corner. Then the fold is straight across, and is 8" long. Any diagonal fold will be longer. Of course, I have no...
*March 30, 2015*

**Calculus**

If the distance is x from P, then the cost is c(x) = 1.5√(x^2+25) + (10-x) dc/dx = 1.5x/√(x^2+25) - 1 = [1.5x - √(x^2+25)]/√(x^2+25) dc/dx=0 when the numerator is zero, or 1.5x = √(x^2+25) 2.25x^2 = x^2+25 1.25x^2 = 25 x^2 = 20 x = 2√5
*March 30, 2015*

**Algebra**

(r^-3s^1/3)^6 / (r^7 s^3/2) r^-18s^2 /(r^7 s^3/2) r^-11 s^1/2 or s^1/2 / r^11
*March 30, 2015*

**Algebra 2**

#1 add the two equations to eliminate y^2: 2x^2=18 x = ±3 #2 multiply by 3 to get 3x^2+3y^2=24 since 3x^2 = 5y^2, 8y^2 = 24 y^2 = 3 #3 just sub in directly: 3x^2-2y^2 = 24 3x^2 - (1/2)(2y)^2 = 24 3x^2 - (1/2)(3x)^2 = 24 6x^2 + 9x^2 = 48 15x^2 = 48 x^2 = 16/5
*March 30, 2015*

**Algebra HELP ASAP**

w(2w-1)=10 2w^2-w-10 = 0 (2w-5)(w+2) = 0 w = 5/2 so, the length is 4
*March 30, 2015*

**calculus**

the distance from (x,y) to (4,-3) is √((x-4)^2 + (y+3)^2) = √((x-4)^2 + ((2x+7)/4+3)^2) = √5/4 (4x^2-20x+61) This has a minimum at x = 37/10 So, the point is (37/10,-18/5) Or, you can consider the perpendicular line through (4,-3). It is y+3 = 2 (x-4) This ...
*March 30, 2015*

**Math**

1x10^-2 = 1/100 lbs = 4/25 oz seems a bit light, but it's a lot closer than 10^-20 = 1/100000000000000000000 lbs!!!
*March 30, 2015*

**calc**

f is increasing where f' > 0 since the even powers are always positive, f'>0 where x-3 > 0 and x-4 > 0 so, that would be (3,4)U(4,∞)
*March 30, 2015*

**Middle Math**

Nope. too many zeros, and wrong number 6E0 = 6 6E-1 = 0.6 ... 6E-7 = 0.0000006 You wrote 7E-8
*March 30, 2015*

**math**

if the discriminant is zero, there is only one root, hence only one point of intersection. positive, two roots negative zero roots Incidentally, you'd better check your discriminant. If you graph y=x+5, you will see that it intersects in two points, not 1. http://www....
*March 30, 2015*

**calculus**

see the related questions below
*March 30, 2015*

**Math**

y = x^(e^x) lny = e^x lnx 1/y y' = e^x(lnx + 1/x) y' = x^e^x * e^x (lnx + 1/x)
*March 30, 2015*

**Calculus**

you have the functions. Just plug in the values.
*March 30, 2015*

**Calc**

(a) dC/dx (b) and (c) are just plug and chug
*March 30, 2015*

**math help**

come on. You have the formula. Just solve n^2+n-1 = 2549 Hint: it's not -51
*March 30, 2015*

**math help**

check the differences: 4,6,8 I suspect that the next terms are 19+10=29 and 29+12 = 41 you plug in 3 pairs of values into a general quadratic y=ax^2+bx+c and you get a+b+c=1 4a+2b+c=5 9a+3b+c=11 a=1, b=1, c=-1 and get Tn = f(n) = x^2+x-1 Or, you can recall that 1+2+3+...n = n(...
*March 30, 2015*

**Mathematics**

((5*.60)+.80)/6 = 63.3% You didn't say whether the tests were weighted, so I'm not sure what the 200 points mean.
*March 30, 2015*

**Algebra**

after t minutes, you want 30+25t = 300-20t
*March 30, 2015*

**Algebra 1**

Find the solution to the system y=x^2-2x-2 My answer is (-1,1)(7,33)
*March 30, 2015*

**Calculus**

well, um, did you try actually drawing the graphs? x=4√y is the right half of a parabola that opens upward y=4√x is the upper half of a parabola that opens to the right. You can think of it as the area in the 1st quadrant, bounded by y=x^2/16 and x=y^2/16 You have ...
*March 30, 2015*

**Math**

3 choices for each of 10 questions is clearly 3^10 Naturally, there is only 1 way of getting all the answers right. If, however, you want to know the order of questions to answer, then there are 10! ways to select the questions. Rather a poorly worded question.
*March 30, 2015*

**algebra**

the difference in heights is 5, so the distance between the tops is the hypotenuse of a 5-12-13 right triangle.
*March 30, 2015*

**Math**

3*4*4, no?
*March 30, 2015*

**exponential equations**

Since 6400 is 16 * 400, the population has doubled 4 times. So, it will take 4*18 minutes.
*March 29, 2015*

**maths**

think of the shape of a wine glass. It's basically a parabola. Not sure what you will do with the linear, since you need a vertical stem and a horizontal base. How about y=0 y=x^2+4 with a suitable domain
*March 29, 2015*

**Algebra**

12 ft^2, but it won't hold much water.
*March 29, 2015*

**arcsin?**

Hmmm. I get tan^-1 (x/3)
*March 29, 2015*

**science**

it's just ∑mv for all the various m and v: 1300(60) + 1500(-95)
*March 29, 2015*

**basic math**

well 66 2/3 percent is 2/3, or 66.67% Simple or compound interest? 66.67% seems a bit high.
*March 29, 2015*

**English**

thank you
*March 29, 2015*

**English**

And if we meet we shall not ’scape a brawl, For now, these hot days, is the mad blood stirring. the fight in which Mercutio and Tybalt are killed or the duel in which Romeo is killed my answer is the 1st one because it was a fight
*March 29, 2015*

**English**

Death lies on her like an untimely frost Upon the sweetest flower of all the field. (Act 4, Scene 5) ow Does this example of dramatic irony create tension? My answer is because the reader know that Juliet is actually sleeping
*March 29, 2015*

**Calculus**

you know that ∫ du/√(a^2-u^2) = arcsin(u/a)+C right? So, just note that 8+2x-x^2 = 9-(x-1)^2 Now go for it.
*March 29, 2015*

**English**

I think that it is the last one.
*March 29, 2015*

**English**

Marry my child early next morn the gallant young and noble gentleman the county paris at st peter church shall happily make thee there a joyful bride Hang thee, young baggage! Disobedient wretch! I tell thee what: get thee to church o' Thursday, Or never after look me in ...
*March 29, 2015*

**English**

What quote from Romeo and Juliet Act 3, Scene 5 illustrates Shakespeare's use of comic relief?
*March 29, 2015*

**Calculus**

since cos(u) < 1, your terms are less than 1/(2^(k/3)+1) sum 1/2^(k/3) converges, and your terms are less than 1/2^(k+3), your series converges
*March 29, 2015*

**English**

thank you
*March 29, 2015*

**English**

Read the following line from Act IV, Scene 5 of Romeo and Juliet, when Capulet speaks of his daughters apparent death: Death lies on her like an untimely frost Upon the sweetest flower of all the field. How does Shakespeare use a simile to emphasize the tragedy of the apparent...
*March 29, 2015*

**math**

a = bh/2 135 = b*15/2 ...
*March 29, 2015*

**Calculus 2 - Series**

yeah - sometimes it's possible to overthink this stuff. It just takes practice, like anything else. Good judgment comes from experience. Experience comes from bad judgment.
*March 29, 2015*

**Calculus 2 - Series**

an = (n + 3)/(2n − 1) well, just start plugging in values for n: a1 = (1+3)/(2*1-1) = 4/1 = 4 a2 = (2+3)/(2*2-1) = 5/3 and so on ... Look at the numerators: 3,4,5,... = n+2 and the denominators: 4,9,16,... (n+1)^2 So, an = (n+2)/(n+1)^2
*March 29, 2015*

**Pre Ap Chemistry**

since PV/T = k is constant, (.825)(566)/(273+15) = P(834)/(273+20)
*March 29, 2015*

**Calculus 2 (Differentiate & Decay Problem)**

#1 you don't have to differentiate. You are given the differentials, and you need to integrate 8sin^2(y) dx + 8cos^2(x) dy = 0 cos^2(x) dy = - sin^2(y) dx dy/sin^2(y) = -dx/cos^2(dx) -csc^2(y) dy = sec^2(x) dx now integrate: cot(y) = tan(x) + c now, since (π/4,π/...
*March 29, 2015*

**Math**

sinC/c = sinA/a sinC = 6.1*0.342/2.1 = 0.993 That is so close to 1, I'd say C=90° So, yes, you are correct. Just a single right triangle does the trick.
*March 29, 2015*

**Algebra 1**

Find the measure of the smallest angle of the right triangle. c= 90degree a= height ac= 7 and cb = 11 a-32.5 degree b-57.5 degree c-13.0 degree d-50.5 degree my answer is a 32.5 degrees
*March 29, 2015*

**Calculus**

a = πr^2 da/dt = 2πr dr/dt So, plug in your numbers. When a = 4π, r=2, so 2 = 2π*2 dr/dt dr/dt = 1/(2π) miles/day
*March 29, 2015*

**Math**

yeah - compound or simple!
*March 29, 2015*

**Math**

the problem will tell you which it is. Although, if it neglects to say the compounding period, it is most likely simple interest.
*March 29, 2015*

**Algebra 1**

thank you
*March 29, 2015*

**Algebra 1**

If the leg of length 11 is adjacent to angle a, you are correct.
*March 29, 2015*

**Algebra 1**

In a right triangle c=90 degrees a=52 degrees b = 38 degrees the base length =11 What is the hypotenuse length? a-6.8 b-8.7 c-14.0 d-17.9 my answer is 17.9 d
*March 29, 2015*

**Algebra 1**

x=1 does satisfy the equation.
*March 29, 2015*

**Algebra 1**

Solve for x sq root 2x+3= sq root 6x-1 a-1 b-2 c-3 dsq root 6 My answer is a = 1
*March 29, 2015*

**Algebra 1**

correct
*March 29, 2015*

**Algebra 1**

A right triangles hypotenuse is 20 cm long. What is themlength of the side opposite a 60 degree angle? a- 40 b- 18.5 c- 20 d- 17.3 My answer is 17.3
*March 29, 2015*

**Algebra 1**

In a right triangle the height = 54 (ba) The hypotenuse is 90 (ac) and the base ism 72 (bc). What is the value of cosC? a-.5 b- .6 c- .8 d- .9 My answer is .8 72/90
*March 29, 2015*

**Geometry**

2(w + w+40) = 500
*March 29, 2015*

**integral calculus**

just apply the power rule to each term ∫ x^n dx = 1/(n+1) x^(n+1) so, ∫ x^4 dx = 1/5 x^5 and similarly for the other terms
*March 29, 2015*

**math**

each face is a triangle with base 8 and altitude 22
*March 29, 2015*

**ALGEBRA**

clearly the compound inequality is an and problem. As for absolute value problems, think of the shape of the graph. It is a V shape. So, if |f(x)| < c, you have one interval, below the line y=c. If |f(x)| > c, then you have the intervals outside the V, making it an or ...
*March 29, 2015*

**maths**

if they are in series, then R = 2+3+r If they are in parallel, then 1/R = 1/2 + 1/3 + 1/r
*March 29, 2015*

**math**

9-m^2 = (3-m)(3+m) So, the (3-m) factors cancel, and you have (3+m) in the top. Not sure just what the other stuff means; your use of numbers and carets is inconsistent. Just recall that u^n/u^m = u^(n-m) whatever u is.
*March 29, 2015*

**Math**

the distance z between you and Jonas after t seconds is z^2 = (60-2t)^2 + (10t)^2 For the box, we know xyz = 500000 since y=2x, 2x^2z = 500000 x^2z = 250000 So, z = 250000/x^2 c(x) = (x)(2x)(3) + (6x)(250000/x^2)(4) + (x)(2x)(5) = 16x^2 + 6000000/x Now just do your minimum stuff.
*March 28, 2015*

**Math**

I went back and checked my figures and I think it should be a t sq root 26
*March 28, 2015*

**Math**

A playground is shaped like a rectangle with a width 5 times it's length (t). What is the simplified expression for the distance between opposite corners of the playground? a- tsq root 26 b- 5t c- 26t squared d- 6t my answer is d 5t 5t+t =x x=6t
*March 28, 2015*

**Math**

Simplify 6/sq root 3 +2 My answer is 12 - 6 sq root 3
*March 28, 2015*

**Math**

thank you
*March 28, 2015*

**Math**

A surfer drives his dune buggy out into the sand dunes.He follows his compass 10 miles due north and then turns due west. If he ends up approximately 35 miles from where he started how far west did he travel? a- 10 miles b- 25 miles c- 33.5 miles d- 35 miles My answer is c 33....
*March 28, 2015*

**Math--MS SUE!**

#1 24 #2 46 #3 70
*March 28, 2015*

**Math**

Good job, Reiny. I keep seeing 3^√ being used as cube root, so maybe I was way off. In any case, the problem is solved.
*March 28, 2015*

**Math**

let f(x) = x^3 - 7 so f(∛7) = 0 See http://keisan.casio.com/exec/system/1244946907 just enter your function, its derivative, and initial guess.
*March 28, 2015*

**Earth Space Science**

you are correct.
*March 28, 2015*

**statistics**

so, do you have a table of NBA players' heights? If so, just do what the exercise says.
*March 28, 2015*

**Math**

I get XB=6 How far do you get? Hint: parallel lines indicate similar triangles.
*March 28, 2015*

**Trigonometry**

Usage differs, but one of them is the single value -π/3, and the other is -π/3+nπ check your text to see what is expected of you.
*March 28, 2015*

**Trigonometry**

just factor the first one, then there will be two values between 0 and 2π, and all multiples of 2π added thereto. 2sin^2(x)-5 sin(x)-3=0 (2sinx+1)(sinx-3) = 0 sinx = -1/2 sinx = 3 (not a valid solution) The other is already factored: (cos(x)-((√2)/2))(sec(x)-1...
*March 28, 2015*

**Trigonometry**

tan(-π/4) = -1 so, θ = -π/4 + nπ sin(π/6) = 1/2, so θ/2 = π/6,5π/6,... θ = π/3, 5π/3, ... = π/3 + 4nπ, 5π/3 + 4nπ
*March 28, 2015*

**Trigonometry**

(2sinx-√3)(2sinx+√3) = 0 sinx = ±√3/2 x = π/3, 2π/3, 4π/3, 5π/3 cos(3x) = -1 so 3x = π,3π,5π x = π/3, π, 5π/3
*March 28, 2015*