Thursday

July 31, 2014

July 31, 2014

Total # Posts: 10,590

**Calculus-ODE**

Start with solving for the complementary solution to the homogeneous equation 2y"+3y'+y=0, the characteristic equation is 2r²+3r+1=0 which is an algebraic equation which can be factorized into (2r+1)(r+1)=0 or r={-(1/2), -1} The complementary solution is therefor...

**math**

Proportions: 100% : 1.75 hours x% : 1 hour x=1*100%/1.75

**math**

Use time = 1/(1/M+1/R)

**math**

2=1/(1/6+1/B) => B=1/(1/2-1/6)=3

**math**

1/(1/20+1/30+1/10) =60/11 minutes

**math**

1/(1/6+1/5.5+1/2.2) =1.245 DAYS

**algebra**

√(75) =√(25*3) =√(5²*3) =5√3

**math**

2³=?

**gen physics**

The centre of gravity is located at a point such that the product of mass multiplied by the distance to the C.G. is equal, namely: Let x = distance from mA, then 50-x = distance from mB. mA*x = mB(50-x) solve for x, and hence 50-x.

**gen physics**

apparent ρ=7860-1000=6860 kg/m² Tension in wire =apparent weight =apparent mass*g =(0.154³)*6860*9.81 N =246 N (approx.)

**physics**

ω2=ω1)+angular acceleration*time or time = (ω2-ω1)/angular acceleration =(0.28-0)/0.021 =40/3 sec.

**Math**

Please comment on the previous answer before reposting: http://www.jiskha.com/display.cgi?id=1373921871

**math :)**

You're welcome. :) The method above is correct, but the final result should be 2 7/24 lbs, since 2*24=48, and 55-48=7. Sorry for the oversight.

**math - addition of fractions**

The question requires us to add three fractions, with different denominators. The first step is to find a common denominator which is the LCM (least common multiple) among 3,4 and 8. Since 4 divides 8, so 4 need not be accounted for. The LCM of 3 and 8 is just the product 24, ...

**Geomtry**

I have a different interpretation of the problem. If I were to assume "three sides" as one length (parallel to the canal) and the two other sides perpendicular to the canal, then we are only fencing three sides on land, and the fourth side is bounded by the canal. Le...

**math**

240.75 is correct.

**Math**

From the knowledge of divisibility, we know that 2 is a factor (all even numbers). That reduces 2002=2*1001 Again, the difference of sums of alternate digits equals zero (1+0)-(0+1)=0, so it is divisible by 11. That makes 2002=2*11*91 We should (try to) know all prime factoriz...

**Math**

She cannot subdivide the equilateral triangle into 2 isosceles triangles. This is the smallest N which is impossible. She can subdivide it into 3 congruent isosceles triangles by joining the centroid with each of the vertices. Each triangle is then 30-30-120 as angles. Each of...

**Calculus**

The idea is to find the family of lines perpendicular to L:7x+5y-2=0. Out of that, we find the particular line L1 passing through P(-6,-2). The intersection of L and L1 gives the required point (closest to P). Family of lines perpendicular to L passing through P0(x0,y0): L : 7...

**Statistics**

With replacement, the probability of selecting a good apple stays at 60/80=3/4. For a two-step experiment, the probability is the product of individual steps, hence, probability of select a good apple in each pick is (3/4)^2=9/16

**maths**

Two trains with speeds s and s+5 km/hr. Initial distance=340 km final distance = 30 km Total distance travelled = 340-30=310 km Total speed = s+s+5=2s+5 Time = 2 hrs Form equation equating distance travelled Time*speed=distance, or 2(2s+5)=310 2s+5=155 2s=150 s=75 Speeds of tr...

**French**

"J'ai faim" is the proper expression to say "I am hungry." Just like in English we would not say "I am hunger", it would be incorrect say the equivalent in French. Another notable difference in French from English is about age. We would say &q...

**object oriented programming**

Can you show us your pseudocode as a start?

**trig**

Parentheses are assumed missing. Implied parentheses are ALWAYS required in numerator and denominator of fractions. (cos^2x+sin^2x)/(cot^2x-csc^2x) This problem can be solved by converting all functions in terms of sine and cosine according to the standard definitions. (cos^2x...

**Java programming- simulation of rolling dice**

You have made the arrays die1...die4 to do two things: 1. as a counter (accumulator) for the frequency, and 2. as the value of the face. This is an impossible task, and that explains why the total adds up to more than a million. I suggest you make the following changes: 1. Add...

**Elementary mechanics**

Use the kinematics equation: Vf=Vi+at where Vf=final velocity=i-2j (m/s) Vi=initial velocity, yet unknown a=acceleration=F/m (in vector form) t=time=10 s a=(2i+7j)/5=0.4i + 1.4j Vf=(i-2j)+(0.4i+1.4j)(10) =(i-2j)+(4i+14j) =5i+12j

**Computers C++**

What are your thoughts?

**GEOMETRY (SA oftriangular pyramid)**

In the calculations of surface area of a pyramid, the height is not required if the apothem (slant height) is given. The height is required, however, to calculate the volume of a pyramid. In fact, the height h is not consistent, because h should always be less than the slant h...

**GEOMETRY (SA oftriangular pyramid)**

Lateral surface area =perimeter of base * apothem /2 =3b*s/2 (for a regular pyramid with a triangular base) Area of triangular base with side b =(√3)*b/2*(b/2) =(√3)b²/4

**math:units conversion**

Convert 6 cm to mm = 60 mm. Now add 60mm to 4 mm to get your answer.

**Math**

If each team plays with each of the other four teams N times, then the number of games played would be: 4, 8, 12, ... Can you find which of the five numbers does not belong?

**College Algebra**

Start with (x-(-1/6))(x-(-8/9))=0 Multiply by 54 on both sides to get (6x+1)(9x+8)=0

**trig**

Convert all three functions in terms of sine and cosine, hence simplify.

**statistics**

Possible typo in bold: "Playing game of chance and pay 300 by rolling a fair die one time if you rome a 2 and receive $1300 if you roll a 4 or six you receive $900 if you ore a 3 5 or one receive nothing. find expected value for this game. based on value is it a good game...

**statistics**

Binomial distribution: - large population=>probability is (almost) constant - p=0.5 (men) q=(1-0.5) (women) - random independent multiple trials N=9 - 2 possible outcomes at each trial P(7)=C(9,7)*p^7 * q^2 =(9!/(2!7!))*0.5^7*(1-0.5)^2 =0.07 (approximately)

**Calculus**

See: http://www.jiskha.com/display.cgi?id=1373656357

**Linear Equation**

Let x=number of gallons of regular sold then 220-x=number of gallons of premium sold Total receipt: 2.20x+2.70(220-x)=519 Solve for x.

**Math :)**

You're welcome!

**Math**

x=(5±(√15)*i)/2 If you do not expect complex roots, please check for typos in the original question.

**Math**

x/(x-2) + (2x)/[4-(x^2)] = 5/(x+2) This calls for finding the common denominator, and then solving for x using the numerators. Do not forget to exclude the asymptotes values of x where the denominator becomes zero. LCM (lowest ommon multiple) of denominators (x-2), (4-x²)...

**algebra1 HELP PLEASE Thanks you!!**

y=√(64*25)=√(40²)=40 f.p.s.

**algebra1 HELP PLEASE Thanks you!!**

Not sure if there is a typo in your question, the speed is y(x)=5√(x)=5√(25)=25 This corresponding an equivalent acceleration approximately that of Mars.

**maths**

18+0.5+2.5=?

**maths**

The idea is to convert f(x)=asin(x)+bcos(x) into the form g(x)=k*cos(a+φ) where k and φ are constants dependent on a and b. This way, it is easy to show that the max/min values of the f(x) is ±k. Start with expanding g(x) using compound angles. g(x) =k(cos(φ...

**Maths**

See: http://www.jiskha.com/display.cgi?id=1373620166

**Math**

First find the rule of the parabola: We know that the parabola curves (is open) towards the bottom, so the rule is y(x)=b-ax² if we set the y-axis to cut the vertex. Since y(0)=16=b, so b=16 or y(x)=16-kx² Also, y(4)=0 tells us that k=1, or the rule of the doorway is...

**alg2 check?**

Remember that ^ has higher precedence than * or +, so in these expressions, parentheses are required: 1. (2)(3)x^(1+3) =6x^4 2. (4)^3 x^(1*3) y^(2*3) =64 x^3 y^6

**Math.**

Two step experiment: multiply the probability of each step. A. P(Jeans,t-shirt)=0.3*0.6=0.18 B. P(jeans, ~t-shirt)=0.3*(1-0.6)=0.12

**Math- important!!!**

Use binomial distribution, p=0.28, q=(1-0.28)=0.72 A) n=5 P(3/5)+P(4/5)+P(5/5) =3C5*p^3*q^2 + 4C5*p^4*q^1 + 5C5*p^5*q^0 =10(0.28^3)(0.72^2) + 5(0.28^4)(0.72) + 1(0.28^5)(0.72^0) Use your calculator to find the answer for (A) B) Expected value for binomial distribution with n=1...

**physics**

150 * 2*3600 j + 250 * 10*60 j =1230000 j =1.23 Mj

**differential calculus**

Intuitively, the circle has a bigger area for the same circumference, so we try to make a bigger circle. Also, since the area increases as the square of the circumference, we want to make 1 single shape as opposed to two. So intuitive answer is to make the smallest square poss...

**French**

Each country name has a gender and a number. The country France is feminine singular, as demonstrated by the phrase "Vive la France!" The country United States (Les États-Unis) is masculine plural. For feminine country names, we use the preposition "en&qu...

**math**

The question does not give the required context. Some countries charge sales tax on labour, and some may not. I believe Overhead rate would be added to the labour, meaning that for every $12 paid to the worker, the customer pays $12(labour)+$15(overhead)=27. If sales tax does ...

**Computer Programming**

Your code seems to be in reasonable shape, except that it does not yet implement the algorithm to find the maximum revenue. So the current revenue is 600*50=30,000$ a month. Your program will increase the rent by $40 steps and recalculate the revenue. When the revenue starts t...

**MATH:( Base systems?!**

Divide the number by the base and note the remainder on the right. The digits from bottom to top is the number required. Example: Find 37 to base 5. 37 R 2 (37/5=7 R2) 7 R 2 (7/5=1 R2) 1 So the number is 1225

**Number and Operations**

3,6,9 and 18, since 20/18 also has a remainder of 2.

**math**

The question should have read: There are 35 students in a class who stu dy either art, music or both. 15 study art. Twice as many students who study art study music. COMPLETE THE VENN DIAGRAM TO SHOW. 35 students in all 15 study art 2*15=30 study music so 35-30=5 study only ar...

**Math 17 Synthetic Division**

Showing steps of synthetic division requires lining up many numbers vertically, which is impossible to do at this web site. I suggest you refer to examples of sites which can format number displays. Try for example: http://www.purplemath.com/modules/synthdiv.htm

**GEOMETRY LATERAL AND SURFACE URGENT (PLEASEHELP)**

Total surface area of a rectangular box =2(lw+wh+hl) where l,w,h=length, width and height respectively. Total surface area of a cubical box (all sides equal to "a" =6a² Total surface area of a Rectangular prism : see above for rectangular box

**Math**

solid: square pyramid height, h = 15 side of base, s = 5 Area of base, Ab=5^2 area of cross section at height y =Ab*(y/15)^2 Volume (using the general solid integral formula based on Simpson's rule) V=(Area at top + Area at base + 4*area at mid-height)*height/6 =(0+25+4*6....

**Prisms**

See: http://www.jiskha.com/display.cgi?id=1374407375

**Number System**

Subtraction is done as in decimal, one digit at a time from the right. Borrow from the left digit if necessary. If the result is expected to be negative, reverse the subtraction (to get a positive difference) and then change the sign. Example: 1101 -0110 ----- 0111

**Number System**

Not sure if the question was quoted properly, because the last group of the first number has only three digits. To add two binary numbers, we add a digit at a time just like in decimal, using the following rule: 0+0=0 0+1=1 1+0=1 1+1=0 with a carry of 1 So to add 101 to 111 we...

**Number System**

You can convert too hex from binary by grouping, from the right, four digits at a time: 1 1011 1011 and convert each group from binary to a decimal digit, using A for 10, B for 11...and F for 15. For example, 1011=> 8+0+2+1=11=>B so the above example becomes 1BB in hex.

**Computer Programming**

I suggest you give it a try and post any difficulties you encounter. Programming is not as hard as it seems once you get started.

**Math**

Width = x inches (given) Length = 2x inches(given) Height = 5 inches (given) Volume = 5*x*2x = 10x² in.3

**Math (please help me Steve)**

Here's a lower bound solution. You may want to investigate other possibilities. The number 7 can be partitioned into 3 ascending non-negative integers in 8 ways, namely: 007# 016 025 034 115# 124 133# 233# There are 3 permutations of partitions (indicated #) with non-disti...

**Math**

Both, in a minute and in an hour. The LCM of 3, 5 and 10 is the same as the LCM of 3 and 10 because 5 divides 10 (5 is a factor of 10). The LCM of 3 and 10 is 30. So the soonest the will flash together is 30 seconds.

**Vba**

First, the concept of sub programs is to isolate a particular calculation and make a "black box" which returns a "complicated" answer without having to worry about how it is done. On the other hand, the UI (user-interface) belongs to a separate element of y...

**math**

15 2's = one way 10 2's + 2 5's = 12!/(10!2!) ways 5 2's + 4 5's = 9!/(5!4!) ways 6 5's = one way Total=194

**Calculus**

Think of f(x)=f1(x)+f2(x) where f1(x)=x f2(x)=-cos(x) We note that f1(x) is monotonically increasing throughout [-π, π) while f2(x) is increasing between [-π, 0) and decreasing between [0,π). Therefore to find the absolute maximum and minimum, we only need to check...

**Statistics/Probability**

The sum P(RR)+P(PP)+P(SS)=0.3288 which rounds to 0.33.

**Statistics/Probability**

A is correct. I assume you know that rock wins over scissors, paper wins over rock, and scissors wins over paper. For the other parts, make a tree diagram complete with corresponding probabilities and sum all the appropriate outcomes to get the probability. Example: R=rock, P=...

**math**

Let x=length of one of the equal sides. Then 42=16+x+x Solve for x.

**Math**

Z1=(2-5.5)/3.5=-1 Z2=(9-5.5)/3.5=+1 Look up the normal distribution table to find P(Z1<Z<Z2)

**physics**

Wavelength = Speed/frequency Speed of light: 3*10^8 m/s Frequency = 3*10^9 Hz Wavelength = 3*10^8/(3*10^9) = 0.1 m = 10cm

**heeeeeelp math**

Not too sure the point of the question, but here's the answer anyway, assuming b and c are given but unknown constants. To find (max|f(x)|) for x∈[-10,10]: Complete squares to get f(x)=(x+b/2)²+c-b²/4 where (-b/2, c-b²/4) is the vertex. If -b/2 ∈...

**heeeeeelpm math**

Continued from http://www.jiskha.com/display.cgi?id=1373027417 Can you show an idea of your probability tree to make sure that your interpretation corresponds to what was asked? What did you get for your answer?

**(pls help) physics**

Q1 1kg = 1000 g It does not make sense to use a bucket of 1.5kg to pull up 10 g of water. You must mean 10 kg of water. 1.5kg+10kg=11.5 kg Work done = mgh (in consistent units) =11.5*9.8*8 j Q2 The word "average" has been used very vaguely. If it means to calculate t...

**physics**

Displacement = "distance" due north (requires speed and direction)

**physics**

Please type your post in "proper case", i.e. use lower case except for the first letter of a paragraph, sentence, or proper nouns. In posts, we use all uppercase only when we mean to SHOUT at someone. "Density bottle" is also called a specific gravity bottl...

**Math (Geometry)**

That's true, it should be the supplement of asin()=180-31.6=148 (nearest degree).

**Math (Geometry)**

See: http://www.jiskha.com/display.cgi?id=1373027638

**math**

Check: 12+12=24 3(12-4)=3*8=24 So answer is correct.

**math**

Make a probability tree. If the first one is white P(W)=6/10 P(WB)=(6/10)(4/9)=24/90 If the first one is black: P(B)=4/10 P(BB)=(4/10)(3/9)=12/90 P(XB)=P(WB)+P(BB)=24/90+12/90=36/90=2/5

**math**

The mid-point has coordinates which are the averages of those of A and B: M((-3+3)/2, (2-2)/2) or M(0,0) The length of a segment is obtained by summing the squares of the difference of coordinates, and then take square-root, namely D(AB)=sqrt((x2-x1)^2+(y2-y1)^2) =sqrt((3-(-3)...

**Physics**

Frictional resistance = μN =μmg =μ6.2N Force required = 2.2 N Thus μ6.2 = 2.2 μ=2.2/6.2 = 0.35 approx.

**math - help please**

Use the definition of conditional probability: P(X9|9X) in the previous question. P(X9∩9X)/P(9X) =P(99)/P(9x) =(4/52)*(3/51) / (4/52) =3/51

**probability**

This is a problem of conditional probability. The shortcut to the answer is consider only the outcomes where the first child is a girl, and calculate the probability among those where both are girls. I.E. Ω={GG,GB} favourable outcome: {GG} So assuming all outcomes are eq...

**algebra2**

Make a tree diagram assuming the products are introduced one after the other. Assuming A=success of product 1, and a=failure of product 1, etc. Required probability =P(Abc)+P(aBc)+P(abC) =(1/5)(1/3)(1/2)+(4/5)(2/3)(1/2)+(4/5)(1/3)(1/2) =13/30

**Math**

What is the rest of the question?

**math**

First factor out the common denominator of 12²=144, which then gives automatically the factorization: (3m+4n)(9m-8n)/144

**advanced functions**

From the function: f(x) = (x + 1)(x – 2)(x – 4)² we see that it is a quartic with leading coefficient equal to 1. So the shape of the curve is like a letter W. Since factors (x+1) and (x-2) are distinct, we see that f(x)<0 ∀ xϵ(-1,2). The double r...

**trigonometry**

Up 50', horizontal 200' makes an angle of elevation of atan(50/200)=14° approx.

**Physics**

Downward force due to gravity is F=1368.1 Friction force resisting movement is FF=1127.6 Therefore net downward force =force required to prevent load from sliding down =F-FF =1368.1-1127.6 =240.45 N

**Physics**

mg=4000 N is correct. θ=20° μ=0.3 (assumed static friction) Gravity force along plane F=mg sin(θ) Friction force along inclined plane =μmg cos(θ) direction acts against movement. To move load up slope: Force required =mg sin(θ)+μmg cos(&the...

**Spanish - help required**

help required.

**math**

there are 360 degrees in one revolution. If it rotates at 600 rpm (revolutions per minute), then the angle it goes through in one minute is 600*360°. In one second, divide the above number by 60.

**Chemistry**

Each revolution moves through 360 degrees. So 48 RPM moves through 48*360° in one minute. In two seconds, the angle is 48*360*(2/60) =48*12 =576°

**math**

Draw a diagram and hence deduce that Height=400 sin(40°)

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | **9** | 10 | 11 | 12 | 13 | 14 | 15 | Next>>