Sunday
September 21, 2014

Posts by john


Total # Posts: 6,245

Algebra
Find the number of integer quadruples (a,b,c,d) with 0\leq a,b,c,d \leq 100, such that a and b are the roots of the quadratic equation x^2-cx+d=0, while c and d are the roots of the quadratic equation x^2-ax+b
March 4, 2013

Algebra
x and y satisfy 2^x = 5 and 5 ^ y = 64. What is the value of xy?
March 4, 2013

Algebra
How many integer values of x are there such that |x-3| + 5 < 16 ?
March 4, 2013

Algebra
Alan and Bob are playing with numbers. Starting with the number n=1 they take turns performing arithmetic manipulations with n. Alan goes first and always multiplies n by 3. Bob adds 1 or 2 to the number n, depending on a coin toss. A number is called reachable, if it can ...
March 4, 2013

Geometry
How many ordered triples (a, b, c) of positive integers are there which satisfy the equation a + b + c = 10 ?
March 4, 2013

Algebra
Find the number of integer quadruples (a,b,c,d) with 0\leq a,b,c,d \leq 100, such that a and b are the roots of the quadratic equation x^2-cx+d=0, while c and d are the roots of the quadratic equation x^2-ax+b.
March 4, 2013

Geometry
ABC is a right triangle with AB = 2, BC = 8\sqrt{3} and AC = 14. What is the value of \sec \angle BAC?
March 4, 2013

Calculus
Given that \displaystyle \int_0^4 x^3\sqrt{9+x^2} dx = a, what is the value of \lfloor a \rfloor?
March 4, 2013

Geometry
A 12 by 12 by 12 cube has all its faces painted blue. It is then broken down to 1728 individual 1 by 1 by 1 cubes. The probability that a randomly chosen 1 by 1 by 1 cube has exactly 2 faces painted blue is \frac {a} {b} , where a, b are coprime. What is the value of a+ b?
March 4, 2013

Algebra
How many integers from 1 to 19999 have exactly 15 divisors?
March 4, 2013

Algebra
Alan and Bob are playing with numbers. Starting with the number n=1 they take turns performing arithmetic manipulations with n. Alan goes first and always multiplies n by 3. Bob adds 1 or 2 to the number n, depending on a coin toss. A number is called reachable, if it can ...
March 4, 2013

Algebra
The difference of the cubes of two consecutive odd positive integers is 400 more than the sum of their squares. Find the sum of the two integers.
March 4, 2013

Hard physics
Two equal point charges of 5 µC are on the horizontal axis. One charge is at -10 cm, the other is at +10 cm.? These two charges don't move, they are STUCK, take the potential to be zero at infinity. Find the potential at the following coordinates: (0,0) cm, (0,10)cm...
March 3, 2013

algebra
rachel and rosa each invested the same amount of money in bonds. Rachel got an 8% return on her money and rosa got a 9% return. If rosa's annual interest was $500 more than rachel's, how much did each invest? Do i need a chart for this problem?
March 3, 2013

Chemistry
what is the percent by mass of NaCHO3 in a solution containing 12g NaCHO3, dissolved in 450mL of water?
March 3, 2013

Geometry
Sandy has a long list of 100 suitors. She decides to label them according to if they are tall, dark or handsome. She finds that each of her suitors fall into at least one of the categories, and 65 of them are tall, 76 of them are dark and 53 of them are handsome. If 20 of the ...
March 2, 2013

Physics
train car with mass m1 = 521 kg is moving to the right with a speed of v1 = 7.9 m/s and collides with a second train car. The two cars latch together during the collision and then move off to the right at vf = 5.1 m/s. 1)What is the initial momentum of the first train car? I ...
March 1, 2013

Geometry
Luis has a simple calculator that has buttons for the digits 0 through 9, each of the 4 basic operations (+, - ,*,/ ), and an '=' button. Luis pushes a digit followed by the '+' sign, followed by another digit, followed by the '-' sign, followed by ...
March 1, 2013

chemistry
A 12 g sample of Ne is added to a container that also holds .78 mol of helium gas. What is the partial pressure of helium if the total pressure, after mixing is 2.43 atm?
March 1, 2013

chemistry
Propane reacts with oxygen in a combustion reaction. What volume of carbon dioxide gas is formed when 20 L of propane are reacted with 55.7 L of oxygen?
March 1, 2013

math
Three forces act concurrently on a point P as shown below. Which vector represents the direction of the resultant force on point P?data:image/png;base64,...
March 1, 2013

Geometry
In acute triangle ABC, we have \angle CAB = 34 ^\circ . E is the foot of the perpendicular from B to AC. A point H is on BE is chosen, and X is the foot of the perpendicular from H to AB. What is the measure (in degrees) of \angle of EHX?
March 1, 2013

Physics
Recently, Asteroid 2012 DA14 came within 34,200 km from the center of the earth at its point of closest approach. If the moon goes around the earth once every 27.5 days, what is the ratio of the distance of closest approach of DA14 to the radius of the orbit of the moon?
March 1, 2013

Geometry
ABC is an acute angle triangle with points D and E on BC and AC, respectively such that BE and AD are altitudes. AD and BE intersect at H. If \angle BCA = 39 ^\circ and \angle EBA = 2 \angle DAB , what is the measure of \angle ABC(in degrees)?
March 1, 2013

Geometry
Luis has a simple calculator that has buttons for the digits 0 through 9, each of the 4 basic operations (+, - ,*,/ ), and an '=' button. Luis pushes a digit followed by the '+' sign, followed by another digit, followed by the '-' sign, followed by ...
March 1, 2013

Physics
What current is produced by a ring with a radius of 0.5 m and a uniform positive linear charge density of 1 microCoulomb/m rotatingwith an angular frequency of 4π/s? a. 1 microAmpere b. 3.14 microAmpere c. 6.28 microAmpere d. 12.6 microAmpere
March 1, 2013

Physics
Suppose that you wish to fabricate a uniform wire out of 1 g of copper. (Resistivity = 1.72*10^-8 Ohm-m, density = 8.94*10^3kg/m^3). If the wire is to have a resistance of R = 0.5 ohm and all of the copper is to be used, how long is the wire? a. 1765 m b. 1816 m c. 1.8 m d. 0....
March 1, 2013

Physics
A current of 4.00 A flows through the heating element of heater converting 500 J of electrical energy into thermal energy every second. What is the voltage across the ends of the heating element? a. 2000 V b. 125 V c. 250 V d. 0.008 V e. 0.125 V
March 1, 2013

English
Can someone tell me if my sentences are correct, please? I'll be very thankful to you. •When I arrived at the hotel, someone was cleaning my room •If I had known that he was so rude, I would have never married him. •You would tell the truth if you were good ...
February 28, 2013

English
Can someone tell me if my sentences are correct, please? I'll be very thankful to you. •When I arrived at the hotel, someone was cleaning my room •If I had known that he was so rude, I would have never married him. •You would tell the truth if you were good...
February 28, 2013

physics
An MP3 player operates with a voltage of 3.7 V, and is using 0.14 W of power. Find the current being supplied by the player's battery.
February 28, 2013

physics
A police car has passed by you with its siren blazing (529-Hz) while traveling at 28.1-m/s. What frequency would you hear after it has passed by?
February 28, 2013

Geometry
Luis has a simple calculator that has buttons for the digits 0 through 9, each of the 4 basic operations (+, - ,*,/ ), and an '=' button. Luis pushes a digit followed by the '+' sign, followed by another digit, followed by the '-' sign, followed by ...
February 28, 2013

Geometry
ABC is an acute angle triangle with points D and E on BC and AC, respectively such that BE and AD are altitudes. AD and BE intersect at H. If \angle BCA = 39 ^\circ and \angle EBA = 2 \angle DAB , what is the measure of \angle ABC (in degrees)?
February 28, 2013

Geometry
The volume of a sphere is numerically equal to the surface area of the sphere. If this value is equal to N \pi, what is the value of N?
February 28, 2013

Physics
Recently, Asteroid 2012 DA14 came within 34,200 km from the center of the earth at its point of closest approach. If the moon goes around the earth once every 27.5 days, what is the ratio of the distance of closest approach of DA14 to the radius of the orbit of the moon?
February 27, 2013

Geometry
In acute triangle ABC, we have \angle CAB = 34 ^\circ . E is the foot of the perpendicular from B to AC. A point H is on BE is chosen, and X is the foot of the perpendicular from H to AB. What is the measure (in degrees) of \angle EHX?
February 27, 2013

SCIENTIFIC NOTATION (ALGEBRA
9.04 * 10 to the 9th power
February 27, 2013

SCIENTIFIC NOTATION (ALGEBRA
9.04 * 10^9
February 27, 2013

Math
Altogether 178 people attended the feast. There were 44 more men than women who came. How many men and how men women attended?
February 27, 2013

History
What was the biggest challenge that Abraham Lincoln faced while in office/
February 27, 2013

Algebra
f(x) is a polynomial such that f(1) = 8 and f(3) = 16. r(x) is the remainder when f(x) is divided by (x-1)(x-3). What is r(5)?
February 26, 2013

math
How long is a rectangular strip of land with a width of 5/4 km and an area of 3/4 square km ?
February 26, 2013

Linear Algebra
Prove that If a vector space is of dimension n and a set of vectors spans V, then that set of vectors must be linearly independent.
February 26, 2013

Chemistry
How many moles of NaOH are in 13.2 mL of 3.00 M NaOH?
February 26, 2013

PLEASE COULD SOMEONE HELP ME OUT Physics
Thank you Elena your a life saver :)
February 25, 2013

PLEASE COULD SOMEONE HELP ME OUT Physics
Two long straight aluminum wires, each of diameter 0.30mm, carry the same current but in opposite directions. They are suspended by 0.50m long strings...If the suspension strings make an angle of 3.0 degree with the vertical, what is the current in the wires? Thank you......
February 25, 2013

PLEASE COULD SOMEONE HELP ME OUT Physics
Hi Elena thank you, but this is what I did and i got it wrong sqrt(2π*5.23x10^-2*2700*π*2.25x10^-6*9.8/4*4π*10^-7)= 1.38x10^-4 but it is wrong what did i do wrong aluminum density is 2700 kg/m^3 and 2.25x10^-6 is .30 mm divided by 100 to get meters an then ...
February 25, 2013

PLEASE COULD SOMEONE HELP ME OUT
Two long straight aluminum wires, each of diameter 0.30mm, carry the same current but in opposite directions. They are suspended by 0.50m long strings...If the suspension strings make an angle of 3.0 degree with the vertical, what is the current in the wires? Thank you......
February 25, 2013

port charlotte high
2Nacl +2HCL = 2NaCl + H2 what mass of sodium is required to react with 8.45g of HCl
February 25, 2013

Physics please help
Two long straight aluminum wires, each of diameter 0.30mm, carry the same current but in opposite directions. They are suspended by 0.50m long strings...If the suspension strings make an angle of 3.0 degree with the vertical, what is the current in the wires? please help out I...
February 25, 2013

physics
When two billiard balls of equal mass collide obliquely, the balls will always separate at what angle?
February 25, 2013

Physics please help
Two long straight aluminum wires, each of diameter 0.30mm, carry the same current but in opposite directions. They are suspended by 0.50m long strings...If the suspension strings make an angle of 3.0 degree with the vertical, what is the current in the wires? please help out I...
February 25, 2013

Science
density = mass/volume = 21.6/8 = 2.7g/cm^3
February 23, 2013

Chemistry
A compound which can donate 2 protons is termed dibasic acid. What is the name given to a compound which can accept 2 protons?
February 23, 2013

algebra 1
thr ratio of two integers is 6:13 the smaller interger is 54. find the larger interger
February 21, 2013

biomechanics
need help
February 21, 2013

Chem Will somebody Please help me
The Lab experiment we did today was to analyze an antacid tablets to determine the actual content of NaHCO3. Suppose I dropped the tablets into the beaker and some of the reaction mixture splashed out. Would my final calculated mass of sodium bicarbonate in the tablet be ...
February 20, 2013

science
A car traveling along the highway needs a certain amount of force exerted on it to stop. More stopping force may be required when the car has:
February 20, 2013

physics
the force required to maintain an object at a constant velocity in free space is eaqual to?
February 20, 2013

Chemistry help
The Lab experiment we did today was to analyze an antacid tablets to determine the actual content of NaHCO3. Suppose I dropped the tablets into the beaker and some of the reaction mixture splashed out. Would my final calculated mass of sodium bicarbonate in the tablet be ...
February 20, 2013

physics
An airplane is flying at a constant velocity parallel to the horizontal, and the pilot drops a flare. Assuming that the plane does not change course, where will the plane be relative to the flare when the flare hits the ground?
February 20, 2013

Biology
Please Help Quick,Write The Balanced Chemical Equation For Respiration In An Athlete In A Race.
February 20, 2013

Biology
Please Help Quick,Write The Balanced Chemical Equation For Respiration In Plants.
February 20, 2013

Biology
Please Help Quick,Under Anaerobic Condition,Explain What Happens To Glucose In Yeast And In Humans?
February 20, 2013

Physics
Rapids in rivers occur when the river narrows. Consider a simple river where the cross-section can be modeled as a rectangle 60 m wide and 2 m deep. If the speed of the river water at this point is 1 m/s, what would be the speed of the water in m/s at a point further down ...
February 20, 2013

Please Help Me
Use the equation for the synthesis of hydrogen to answer the following. C (s) + H2O (l) -> CO (g) + H2 (g) deltaH = + 31.3 kcal/mol carbon deltaS = +32 cal/(mol•K) Calculate the energy change (deltaH) when 5.00 g of carbon is consumed. Calculate the energy change (...
February 19, 2013

math
In third grade... Write an equation comparing test scores of 88 and 97. (Use a box for missing number) do you know how to answer this?
February 19, 2013

math
In third grade... Write an equation comparing test scores of 88 and 97. (Use a box for missing number) do you know how to answer this?
February 19, 2013

Chemistry
Use the equation for the synthesis of hydrogen to answer the following. 10 points. C (s) + H2O (l) -> CO (g) + H2 (g) deltaH = + 31.3 kcal/mol carbon deltaS = +32 cal/(mol•K) Calculate the energy change (deltaH) when 5.00 g of carbon is consumed. Calculate the energy ...
February 19, 2013

chemistry
assume the true concentration of the acetic acid solution is .175M and calculate the percent relative error in your measurement?
February 19, 2013

Maths
R=square root of u squared plus v squared divided by m and u and v are positive.Find u when r=3,v=6 and m=5
February 19, 2013

Maths
R=square root of u squared plus v squared divided by m and u and v are positive.Find u when r=3,v=6 and m=5
February 19, 2013

Math
Find the sum of all primes a<1000, such that a^k +1 = b^{m+1} for some positive integers k,b,m.
February 19, 2013

Math
Let S(n) denote the sum of digits of the integer n. Over all positive integers, the minimum and maximum values of S(n)/S(5n) are X and Y, respectively. The value of X+Y can be written as a/b , where a and b are coprime positive integers. What is the value of a+b?
February 19, 2013

Math
John is building a fence that is 6 feet high and 18 feet wide to put around his garden. He has two sizes of boards that he can use. One is 2 feet by 6 feet and the other is 4 feet by 6 feet. John can put the boards either horizontally or vertically and he has lots of boards of...
February 19, 2013

Maths
Siuan's grandmother recently signed up for a twitter account. She only follows five people - her five grandchildren. Each day, each of her grandchildren make two tweets and at the end of the day Siuan's grandmother gets an e-mail that lists all ten tweets in ...
February 19, 2013

Math
Killer robots are trying to take over the world. They know the password to the doomsday weapon is 5 digits long and contains either 0 or 1, and either 2 or 3, and either 4 or 5, and either 6 or 7, and either 8 or 9. If the robots can enter 5 passwords per second, how long (in ...
February 19, 2013

math
"The area of a rectangle is 360m2. If its lengh if increased by 10m and its width is decreased by 6m, then its area does not change. Find the perimeter of the original rectangle." I need to use the "guess and test" or the "draw a diagram" method ...
February 18, 2013

Physics
The Royal Gorge bridge over the Arkansas River is 310.0 m above the river. A 59.0-kg bungee jumper has an elastic cord with an unstressed length of 62.0 m attached to her feet. Assume that, like an ideal spring, the cord is massless and provides a linear restoring force when ...
February 17, 2013

Chemistry
You use 2.80 g of NaHCO3, and determined that 2.83 g of carbon dioxide ar produced. Convert the mass of NaHCO3 to moles: Convert the mass of CO2 to moles:
February 16, 2013

Chemistry
Some of your reaction mixture splashed out of the beaker when you dropped the tablets into the acetic acid. How would this affect your measurements? Woud your final calculated mass of sodium bicarbonate in the tablet be artificially high or low as a result of this splashing?
February 16, 2013

dilution please help
How to use serial dilution to dilute a stock solution at 15000 fold dilution?
February 16, 2013

Dilution
Please, if possible, check if my method of dilution is correct Problem: Given a very concentrated liquid PBS, dilute it to 1:15,000 My approach is to use serial dilution First: dilute it 15x (50ul of PBS + 750ul of water)... this will give 1:15 Second: dilute 10xfold more (...
February 15, 2013

jones
I have a unscramble analogies worksheet that I can't answer. Here are the analogies: ________:judical branch [eempusr ructo] radius:______[meeairtd] brass instruments:_____[stoaercrh] _______:poem[anzsat] _______:pants[bowaerrd] thank yo
February 14, 2013

Chemistry
A solvent has a molar mass of 37.2 g/mol and a normal boiling point of 111.2 oC. The boiling point elevation constant, K b , for this solvent is 1.58 oC/m. If 18.7 g of a nonelectrolyte having a molar mass of 20.5 g/mol are mixed with 170.0 g of the solvent, what is the ...
February 14, 2013

World history; Check:P
I have nothing to add to this... dickbutt
February 13, 2013

College
A bod of 10kg is traveling in straight line at 10m/s (a)what is de momentum?(b)what is de average force required to increase its velocity 4rom zero to 20m/s in 4seconds?
February 13, 2013

Physics
During an action potential, Na^+ ions move into the cell at a rate of about 3x10^-7 mol/m^2*s. How much power must be produced by the "active Na^+ pumping" system to produce this flow against a +30-mV potential difference? Assume that the axon is 40cm long and 30um ...
February 12, 2013

Pre cal
From a point A is 8.20 meters above level ground,the angle of elevation of the top of a building is 31degrees 20 min and the angle of depression of the base of the building is 12degree 50 min. Approximate the heighth of the building
February 11, 2013

Chemistry
Naphthalene combustion can be used to calibrate the heat capacity of a bomb calorimeter. The heat of combustion of naphthalene is -40.1 kJ/g. When 0.8210 g of naphthalene was burned in a calorimeter containing 1,000. g of water, a temperature rise of 4.21ÂÂ&...
February 11, 2013

Math
two sides of a triangle have the ratio of 3:4. The hypotenuse is 20. What are the measures of the two other sides?
February 11, 2013

Physics
A dropping ball initial at rest is dropped 1.5m; calculate a) the traveling time of the ball and b) its velocity just before reaching the ground.
February 10, 2013

probability
John has 3 unique coins such that the probability of obtaining a head when the coin is flipped is 1/10, 2/10 and 3/10, respectively. If he flips each of the 3 coins once, the probability that at least 1 heads appears is p. What is the value of 1000p?
February 10, 2013

probability
John has 3 unique coins such that the probability of obtaining a head when the coin is flipped is 110, 210 and 310, respectively. If he flips each of the 3 coins once, the probability that at least 1 heads appears is p. What is the value of 1000p?
February 10, 2013

Physics please help
During an action potential, Na^+ ions move into the cell at a rate of about 3x10^-7 mol/m^2*s. How much power must be produced by the "active Na^+ pumping" system to produce this flow against a +30-mV potential difference? Assume that the axon is 40cm long and 30um ...
February 10, 2013

Physics please help
Can you please help out am still stuck one this
February 10, 2013

Physics please help
During an action potential, Na^+ ions move into the cell at a rate of about 3x10^-7 mol/m^2*s. How much power must be produced by the "active Na^+ pumping" system to produce this flow against a +30-mV potential difference? Assume that the axon is 40cm long and 30um ...
February 10, 2013

physics
8. Electric field lines arising from two small charged particles P and Q. Consider the following two statements: i.The charge on P is smaller than the charge on Q. ii.The electrostatic force on P is smaller than that on Q. Which of the above statements are true? A) Only i. B) ...
February 9, 2013

Pre-calculus
a) A particular ball always rebounds 3/5 the distance it falls. If the ball is dropped from a height of 5 meters, how far will it travel before coming to a stop? Explain the reasoning. b) Prove that if a1, a2, a3, ... is a geometric sequence,then ln(a1), ln(a2), ln(a3)... is ...
February 9, 2013

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