Tuesday
December 6, 2016

# Posts by Robert

Total # Posts: 969

HELP ! Algebra
Solve the quadratic equation by completing the square. (-x^2 + 6x + 10 = 0)
November 16, 2012

HELP !!! Algebra 2
15. What is the solution of the linear-quadratic system of equations? {y = x^2 + 5x - 3} {y - x = 2}
November 16, 2012

Math for Steve or someone good at math
Okay im not sure if anyone was even right but i dont feel like checking a million times, i got a 3/5 following one of them. The answers are: B 10% increase D 12% decrease A 20% increase D 8% decrease B increase was about 1.1% Please do not listen to the trolls, they just want ...
November 8, 2012

Math for Steve
If you could see WARNING!, Jman, and Emily both replied within 4 minutes. Thats how you can tell they are lying. Josslyn was correct, the other people are the type of people that are banned from the site. (other person* because it was one guy making the names).
November 6, 2012

Statistics
@John I have come from a year later to reply to your concern, to uproot this tyranny that is Math Guru. No longer shall we sit wondering what the other half of the question is. No longer must we be given a formula and have to solve it out. NO LONGER MUST WE SIT THROUGH THIS. ...
November 5, 2012

Statistics
I got only love for John. The answer is fate
November 5, 2012

physics
Since the masses stick together, there is conservation of momentum but no conservation of energy. Let x be the new velocity. Hence, 0.5*0.4 + 0.8*(-0.20) = (0.5+0.8)*x X = (0.2-0.16)/1.3 = 0.0307 m/s KE = 0.5*1.3*0.0307^2 = 0.000615 J.
October 30, 2012

Science
While traveling along a highway a driver slows from 24 m/s to 15 m/s in 12 seconds. What is the automobile's acceleration? How would I show the work and find this answer?
October 29, 2012

Algebra 2
3. Identify the vertex and the axis of symmetry of the graph of the function y = 3(x + 2)2 – 3. (1 point) A- vertex: (2, –3); axis of symmetry: x = 2 B- vertex: (–2, –3); axis of symmetry: x = –2 C- vertex: (2, 3); axis of symmetry: x = 2 D- vertex...
October 25, 2012

chemistry
how many milliliters of 0.250 M KMnO4 are needed to react with 3.55 grams of iron(II)sulfate, FeSO4? the reaction is as follows: 10FeSO4(aq)+2KMnO4(aq)+8H2SO4(aq)¨ 5Fe2(SO4)3(aq)+2MnSO4(aq)+K2SO4(aq)+8H2O(l)
October 23, 2012

chemistry
WHAT IS THE VOLUME IN MILLILITERS OF 0.100 SULFURIC ACID CONTAINING 0.949 GRAMS H2SO4
October 23, 2012

Algebra 2 Helpp :(
QUESTIONS (vvv) (1) Solve the system by subsitution 2x + y = -11 3 - 4y = 11 (2) Solve the system by elimination 2x + 6 = -12 5x - 5y = 10 (3) What is the solution of the following system? -3x - 2y = -12 9x + 6y = -9 (4) What is the solution of the following system? x - y = 11...
October 23, 2012

22. The graph of g(x) is f(x) translated to the left 8 units and up 2 units. What is the function rule for g(x) given f(x) = x²? (2 points)
October 22, 2012

October 22, 2012

21. A candle is 17 in. tall after burning for 3 hours. After 5 hours, it is 15 in. tall. Write a linear equation to model the relationship between height h of the candle and time t. Predict how tall the candle will be after burning 8 hours. (2 points)
October 22, 2012

Ratios of Similar Figures
is number 5 c?
October 22, 2012

nutrition
Jonathan, a two-and-a-half-year-old, lives with his mother and brothers at his grandmother's house in Chicago. His mother, Anita, works at a pharmacy to support the family. Jonathan spends his days at home with his grandmother. While Anita works, his grandmother brings the...
October 18, 2012

Microeconomics - University of Boston
4. If Cassandra bought 16 cotton blouses last year when her income was \$40,000 and she buys 24 cotton blouses this year when her income is \$50,000, then what is her income elasticity of demand? Interpret what the income elasticity of demand you just calculated means to you. ...
October 17, 2012

Microeconomics
4a. In the market for hand-made guitars, when the price of guitars is \$800, annual revenues are \$640,000. When the price falls to \$700, annual revenues decline to \$630,000. Over this range of guitar prices, is the demand for hand-made guitars elastic, unit-elastic, or ...
October 17, 2012

Microeconomics
The producer of X is contemplating a price change and has asked for your advice. After some empirical investigation, you conclude that the price elasticity of demand for X is 1.25. As an economist, what would you advise the producer to do in order to raise total revenue? Would...
October 17, 2012

Physics
In Case A the mass of each block is 4.8 kg. In Case B the mass of block 1 (the block behind) is 9.6 kg, and the mass of block 2 is 4.8 kg. No frictional force acts on block 1 in either Case A or Case B. However, a kinetic frictional force of 9.4 N does act on block 2 in both ...
October 14, 2012

chemistry
in an experiment, 2.50g of salicylic acid is reacted with 10.31g of methanol. the yield of methyl salicylate, C8H8O3, is 1.27g. what is the percentage yield?
October 13, 2012

chemistry
if a reaction vessel contains 11.5g NH3, 12.0g O2, and 10.5g CH4, what is the maximum mass in grams of hydrogen cyanide that could be made?
October 13, 2012

chemistry
in a reaction of 3Cu(s)+ 8HNO3(aq)¨ 3Cu(NO3)2(aq) +2NO(g) + 4H2O(l). if 5.58 grams of Cu(no3)2 is made how many grams of nitrogen monoxide is present
October 12, 2012

chemistry
copper metal reacts with nitric acid. assume that the reaction is 3Cu(s) + 8HNO3(aq) ——> 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l). if 5.58 grams of Cu(NO3)2 is obtained, how many grams of nitrogen monoxide would have formed
October 12, 2012

Science
In the early 20th century, some scientists were reluctant to accept the conclusion that DNA could be the genetic material because it is so_________________.
October 9, 2012

Biology
A bacterium that synthesizes an enzyme that neutralizes an environment toxin would probably use a(n) _____________ operon to regulate production of the enzyme.
October 9, 2012

world history
you should email me, im also in Penn Foster lol we could cut work in half if we work on this crap together.. rvargas1020 @ live . com
October 6, 2012

english 4
Please explain to me how to determine the answer im looking for
October 3, 2012

english 4
if i knew i would not ask
October 3, 2012

english 4
The two waiters exchanged a look whose meaning was clear to me. what type of clause or phase is used?
October 3, 2012

english4
can you explain to me how to determine what type of verbal it is my choices are Participle, Gerund, and infinitive
October 3, 2012

english4
What do you think Ms. Sue
October 3, 2012

english4
Well as the verbal i chose "to be moved" im not sure what type of verbal it is!
October 3, 2012

english4
He will not allow the table to be moved. identify the Verbal in the sentence and type of verbal
October 3, 2012

english4
what type of clause or phrase is used in the sentence: we hit a snag while rowing to shore
October 3, 2012

math
Average Growth Rate(2000-2009)of China - GDP: 10.9 Population: 0.8 Per Capita GDP: 10.1 Ethiopia - GDP: 7.5 Population: 2.8 Per Capita GDP: 4.7 How fast does total output(GDP)have to grow in order to raise per capita GDP in Instructions: Enter your responses to one decimal ...
October 3, 2012

Physics
Max Height = 1,306M Range = 3,840M Hangtime/Total Time = 32 seconds Time to reach max height = 16 seconds
September 30, 2012

English
What are the nouns and verbs in the sentence. Life is full of choices, so I must learn to make good ones.
September 27, 2012

Biochemistry
Acetylcholinesterase catalyzes the hydrolysis of the neurotransmitter acetylcholine: Acetylcholine + H2O  actetate + choline The KM of acetylcholinesterase for its substrate acetylcholine is 9 x 10-5 M. In a reaction mixture containing 5 nanomoles/ml of ...
September 22, 2012

Linear Algebra
awesome, thanks a lot Steve, that link will come in handy!
September 21, 2012

Linear Algebra
Solve the following system using Gauss's algorithm (a) x1 + 2x2 + 4x3 + 6x4 = 3 2x1 + x2 + 3x3 = -6 -2x1 + x2 + 6x3 + 4x4 = -11 2x1 + x2 + x3 = 0 so the matrix will be: 1 2 4 6 3 2 1 3 0 -6 -2 1 6 4 -11 2 1 1 0 0
September 21, 2012

Math
Staring from the pit, Helen made three laps around a circular track at 40 seconds per lap. She than made a 30-second pit stop and two and a half laps before running off the track and getting stuck in the mud for the remainder of the race. Graph Helen's distance from the ...
September 18, 2012

Calculus
Calculate the following integral and determine whether it's convergent, or divergent. integral at [-3,0] x dx / sqr(9 - x^2)
September 15, 2012

calculus
Thanks Reiny and Steve. Now to pass the exam!
September 14, 2012

calculus
Calculate the following integral: ∫ dx / x(1 - √x)^2
September 14, 2012

Calculus
thanks Steve! You're a lifesaver
September 13, 2012

Calculus
Calculate the following integral: ∫ sec^4 (3x)/ tan^3 (3x) dx For this one, can I bring up the tan to tan^-3?
September 13, 2012

Algebra
Algebra Question: A team wins 15 of their first 20 games. If they win only half the time from now on, how many games will they have to play in order to win 60% of their total games? I have it figured out manually, but cant get it in equation form.
September 12, 2012

Calculus - Question
If I go with my first assumption I get this: ∫ sec^4 (3x) tan^-3 (3x) = ∫ sec^3 (3x) tan^-4 (3x) sec(3x)tan(3x) dx = ∫ sec^3 (3x) (sec^-4 3x - 1)sec(3x)tan(3x) dx u = sec(3x) dx du = 3sec(3x)tan(3x) dx > 1/3du = 1/3 ∫ u^3 (u^-4 - 1) du = 1/3 ∫...
September 12, 2012

Calculus - Question
Or do I use the rule of ∫ sec^n x dx divided by the rule of ∫ tan^n x dx?
September 12, 2012

Calculus - Question
Am I allowed to do this? for the integral of ∫ sec^4 (3x)/ tan^3 (3x) dx I change it to ∫ sec^4 (3x) tan^-3 (3x) From here I use the rule for trigonometry functions.
September 12, 2012

Linear Algebra
Last number from the sample test! A plane P passes by the coordinates: A(1,0,-7); B(-2,-1,0); C(0,0,-3) Using the equation of the line D: x= 7+12t, y= -1-6t, z= 2-2t, Find the equation of a line that's entirely part of the plane P and that is perpendicular to the line D at...
September 10, 2012

Linear Algebra 2
This is another question I can't figure out. Given planes pie1 and pie2 defined as: pie1: 2x + 5y - 7x + 2 = 0 pie2: x + y - z + 3 = 0 (b) Give the equation of the line of intersection of these two planes. I only found the answer for (a) where they ask to find the angle ...
September 9, 2012

Linear Algebra
THanks again Mate! You've been a big help lately, I really appreciate it.
September 9, 2012

Linear Algebra
So I'm studying for my first exam and I'm stuck on this number. Given both lines: D1: (x,y,z) = (2,0,0) + k(0,3,0) D2: (x,y,z) = (2,0,2) + k(0,0,1) (a) Give the algebraic equation of the plane containing both lines. I know that I have to start off by finding the ...
September 9, 2012

Linear Algebra
THanks Mate!
September 8, 2012

Linear Algebra
2 people move in the same direction along a line of equation: (x + 3)/10 = (y + 10)/20 = (z - 10)/-20 Mobile M1 is at a point A(-3, -10, 10) and moves at a velocity of 6m/s towards point B(7, 10, -10) where Mobile 2 is found, walking in the same direction at a velocity of 3m/s...
September 8, 2012

Calculus
THanks Steve and Reiny!
September 7, 2012

Calculus
Hello, I just wanted to verify if my work was good. Calculate the following integral by parts: ∫ upper limit is 1/5 and lower limit is 1/10. of 10sin^-1 (5x)dx so first I named the variables: u = 10 sin^-1 (5x) du = 50 / sqr(1-25x^2) dv = dx v = x so we get: = 10 sin^-1...
September 7, 2012

Definite integral by parts (correction)
Hello, I just wanted to verify if my work was good. Calculate the following integral by parts: ∫ upper limit is 1/5 and lower limit is 1/10. of 10sin^-1 (5x)dx so first I named the variables: u = 10 sin^-1 (5x) du = 50 / sqr(1-25x^2) dv = dx v = x so we get: = 10 sin^-1...
September 5, 2012

Math
Knowing u = (4,0,-3), v = (x,3,2) and that the orthogonal projection of v on u is a vector of norm 6, determine x. Thank you
August 27, 2012

Linear Algebra
Ok this is the last one I promise! It's from a sample exam and I'm practicing for my finals :) Verify if the following 4 points are consecutive vertices of a parallelogram: A(1,-1,1); B(3,0,2);C(2,3,4);D(0,2,3) (b) Find an orthogonal vector to the plane containing the ...
August 27, 2012

Linear Algebra 2 question
sorry I wrote D, but there is no D, just AB and C
August 26, 2012

Linear Algebra 2 question
Hello, I have another question from my linear algebra class. I'm asked to find the area of a triangle using determinants, but they don't give me the vertices, only the sides. Where A,B,C and D are the vertices, u and v are 2 out of the 3 sides. Now they give me u=(-3,1...
August 26, 2012

Linear Algebra
Knowing u = (4,0,-3), v = (x,3,2) and that the orthogonal projection of v on u is a vector of norm 6, determine x. Thank you
August 26, 2012

science
1.How many meters away is a cliff if heard one half second after the original sound? Assume that sound travels at 343m/s on that day
August 21, 2012

Physics - Electromagnetism 2
Two coils, held in fixed positions, have a mutual inductance of 165 µH. What is the peak emf in one coil when the current in the other coil is I(t) = 16.0 sin(1.15 103t), where I is in amperes and t is in seconds? Just a few hints on how to start it off would be very ...
August 16, 2012

Physics - Electromagnetism
An inductor in the form of a solenoid contains 440 turns and is 15.8 cm in length. A uniform rate of decrease of current through the inductor of 0.421 A/s induces an emf of 175 µV. What is the radius of the solenoid?
August 16, 2012

Physics 2
thanks. It's all good, I understand your approach and I really appreciate it!
August 14, 2012

Physics 2
thank you very much drwls, this is a question from a sample exam, getting ready for my finals tomorrow!
August 14, 2012

Physics 2
the character that doesn't show up is the emf (E)
August 14, 2012

Physics 2
Show that during the charging of the capacitor in an RC circuit, the charge of the capacitor, as a function of time, is: q(t) = C(1 – e-t/RC)
August 14, 2012

Physics - Electromagnetism
A charge +q is at the origin. A charge –2q is at x = 2.00 m on the x axis. For what finite value(s) of x is (a) the electric field zero? (b) the electric potential zero?
August 14, 2012

enviroment
The surroundings or conditions in which a person, animal, or plant lives or operates.
August 13, 2012

Physics - Electromagnetism
A square loop (length along one side = 20 cm) rotates in a constant magnetic field which has a magnitude of 2.0 T. At an instant when the angle between the field and the normal to the plane of the loop is equal to 20 and increasing at the rate of 10/s, what is ...
August 12, 2012

Physics - Verification
Two long straight parallel wires separated by a distance of 20 cm carry currents of 30 A and 40 A in opposite directions. What is the magnitude of the resulting magnetic field at a point that is 15 cm from the wire carrying the 30-A current and 25 cm from the other wire? So I ...
August 12, 2012

Life Science
10 Microsporidia Chytridiomycota Neocallimastigomycota Blastocladiomycota Zoopagomycotina Kickxellomycotina Entomophthoromycotina Mucoromycotina Glomeromycota Dikarya
August 12, 2012

math
61-43 (Goal % and current %) = 18 % 18% / 0.6% = 30 years
August 12, 2012

Art Appreciation
Discuss how art was used as a vehicle for propaganda, and whether such use is present in the works of Höch, Grosz, and Picasso. Use one example from Gardner's Art through the Ages and one from the Internet.
August 9, 2012

Calculus - Riemann Sum
Given a function f(x) = squr(3 + 2x), on [-1,1], subdivided into 4 equally large intervals, calculate the Riemann sum SR4 = 4Ei=1 f(xi)delta(x). my attempt at the solution: [-1,1], a = -1 and b = 1 delta(x) = 1 - (-1)/n = 2/n xi = a + delta(x)i xi = -1 + 2/n(i) so after adding...
August 6, 2012

Math
so for (a) you used Y = Yo + Vot+ 1/2at^2 so when you derive it, you get time for the other ones, got it. THanks a lot Reiny
August 6, 2012

Calculus
oops, that was under my brother's name hehe
August 6, 2012

Calculus
Solve the differential equation dy/dx = -xe^y and determine the equation of the curve through P(1,2) I tried solving the differential equation and I get y = log(x^2/2 + C). Is this correct? Now I forgot how to find the equation. Thank you!
August 6, 2012

Chemistry 2
oh okay, well in that case there's no change? Nothing happens to the ethanol and we get the same K constant that we had previously?
August 3, 2012

Chemistry 2
oh this is just a theoretical question. It's about the hydrolysis of ethyl acetate, it gives ethanol and acetic acid as the products
August 3, 2012

Chemistry 2
Supposed you stoppered the flasks after your titration to determine the equilibrium constant and kept the solutions for another day so that the equilibrium was re-established. What would happen to the amount of ethanol present? What would be the relationship of the original ...
August 3, 2012

Chemistry
okay thanks Dr.Bob, that's exactly what I did too.
August 3, 2012

Chemistry
because it's a 1:1 ratio for all, then at rxn, we would have -x for both EtAc and H2O and + x on the right, so x = 0.03045. Is this correct?
August 3, 2012

Chemistry
does it mean that because acetic acid has 0.03045 mol at equilibrium that x = 0.03045 mol? So then Ethanol would also have 0.03045 mol at eq and EtAc and H20 would both be their initial [conc] - x?
August 3, 2012

Chemistry
Find the equilibrium moles for the following reaction with initially 0.051 mol for Ethyl acetate, 0.260 mol for water and 0.03045 mol of acetic acid at equilibrium. I'm not sure how to get the ones at equilibrium for the left side or even how much you have to take away for...
August 3, 2012

CHemistry- For Dr.Bob
Awesome, it's all clear now, thanks a lot again!
August 2, 2012

CHemistry- For Dr.Bob
Yes I see my mistake now, because they first ask to find the moles of NaOH used, so would it simply be 0.015 mol? If I remember you had a density of HCl solution and the mass of that solution was mass = volume x density = 5 mL x density in g/mL = ? g. You can estimate the mass...
August 2, 2012

CHemistry- For Dr.Bob
Hey Dr.Bob, I asked two days ago a question about a titration lab I had that you answered, but I still have one more question about that lab. Here's the lab summary: For my chemistry of solutions class, we had a titration lab where we titrated NaOH into an HCl + H2O mix. ...
August 2, 2012

Chemistry - titration lab
Amazing, thank you DrBob!
July 31, 2012

math
Which number property shows that the two sides of the equation are equal? 841 + 841(37) + 841(623) = 841 + 841(37 + 623)
July 29, 2012

Physics - Electromagnetism
thank you Elena!
July 25, 2012

Physics - Electromagnetism
This is the last question for a final exam preparation sheet and I can't figure out the answer. Any help would be greatly appreciated. Thank you. - One very long wire carries current 10.0 A to the left along the x axis. A second very long wire carries current 75.0 A to the...
July 25, 2012

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