# ERIKA

Popular questions and responses by ERIKA-
## Indefinite Integrals

find the indefinite integral of (1/x)*(e^(-2log[ 3,x])) dx where 3 is base of the log i cannot even figure out where to start :( please help. thank you

*asked on May 24, 2013* -
## calculus

With x people on board, a South African airline makes a profit of (1104 − 3 x) rands per person for a specific flight. A. How many people would the airline prefer to have on board? Answer: x= B. What is the maximum number of passengers that can board

*asked on November 1, 2010* -
## Math

After dinner, three friends at a restaurant paid their bill and noticed a bowl of mints on the front counter. Sean took one-third of the mints but returned four because he had a momentary pang of guilt. Fred then took one-fourth of what was left but

*asked on February 22, 2015* -
## Calculus

Suppose that the machinery in question costs $104000 and earns profit at a continuous rate of $69000 per year. Use an interest rate of 9% per year, compounded continuously. When is the present value of the profit equal to the cost of the machinery? Round

*asked on December 1, 2010* -
## Maths

Let r'(t) represent the rate of growth of a dog in pounds per year. What does r(t) represent? What does integral of 2 to 6 r'(t) represent about the dog?

*asked on November 16, 2016* -
## Calculus

The following table gives the percentage, P, of households with a television set that also have a VCR. (Unlike the data in your textbook, this data is ficticious). Year 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 % having VCR 0.2

*asked on November 5, 2010* -
## Math Measurements

If the length (L) of the prism is 10 inches, and each rectangular face has a width (W) 2ã3 of inches, determine the total surface area of the prism in square inches. Round your answer to the nearest inch.

*asked on October 17, 2008* -
## geometry

The perimeter of triangle ABC is 13 cm. It was dilated to create triangle A'B'C' The perimeter of triangle...is cm

*asked on August 31, 2016* -
## Calculus

The temperature of a cup of coffee varies according to Newton's Law of Cooling: dT/dt = -k(T - A), where T is the temperature of the tea, A is the room temperature, and k is a positive constant. If the water cools from 100°C to 80°C in 1 minute at a room

*asked on June 4, 2019* -
## computer science C++

The variables arr1 and arr2 have been declared as pointers to integers. An array of 10 elements has been allocated, its pointer assigned to arr1, and the elements initialized to some values. Allocate an array of 20 elements, assign its pointer to arr2,

*asked on February 15, 2012* -
## chemistry

A sample of argon at 300.°C and 50.0 atm pressure is cooled in the same container to a temperature of 0.°C. What is the new pressure?

*asked on October 30, 2009* -
## Science

Why are there so many villi and air sacs?

*asked on February 7, 2011* -
## math help please

The distance a spring stretches varies directly with the force applied to it. If a 7-pound weight stretches a spring a distance of 24.5 inches, how far will the spring stretch if a 12-pound weight is applied?

*asked on January 12, 2016* -
## physics

a car is moving down a street at 55km/h.A child suddenly runs into the street. If it takes a driver 0.75s to react and apply the brakes, how many meters will the car have moved before it begins to slow down?

*asked on February 4, 2012* -
## Calculus

At a price of $7.5 per ticket, a musical theater group can fill every seat in their 1550 seat performance hall. For every additional dollar charged for admission, the number of tickets sold drops by 55. a) What ticket price maximizes revenue? Round your

*asked on November 3, 2010* -
## Chemistry

What is unusual about thymol blue? Why does thymbol blue change color at the pH that is does?

*asked on February 14, 2012* -
## CHEMISTRY

2C2H2+ 5O2-> 4CO2+ 2H20. If 1 mole of C2H2 reacts with oxygen, how many moles of C02 are produced.

*asked on September 28, 2012* -
## Chemistry

How do you find the Ka1 and Ka2 of oxalic acid when it is in a solution that is 1.05 M H2C2O4 and has a pH of 0.67. [C2O4^2-] = 5.3x10^-5 M. I have tried using an ICE table for both reactions, as oxalic acid is a diprotic acid, but I am having trouble

*asked on November 1, 2015* -
## calculus

The ellipse x^2+3y^3=13, has two points when x+-1 . Find the slope of the ellipse at both these points. 2. Thoroughly explain the method you used to find the slope in part 1. What are the strengths and weaknesses of the method you used? 3. Explain whether

*asked on January 3, 2013* -
## philosophy

According to Renaissance philosophy, commoners often represent?

*asked on July 30, 2010* -
## algebra

morgan saw 10 blue cars 8 red cars and 42 white cars drive by her house in 1 hour what is the experimental probability that the next car will not be white

*asked on March 12, 2015* -
## bilogy

methane which is composed of carbon and hydrogen, lacks !@#$%^&tional groups and is a gas at room temperature.upon replacing one of the hydrogen atoms with a hydroxyl group, methane is converted to a liquid called methanol at room temperature. please

*asked on December 14, 2010* -
## Finance

Bread, Inc., has an odd dividend policy. The company has just paid a dividend of $6 per share and has announced that it will increase the dividend by $4 per share for each of the next five years, and then never pay another dividend. If you require an 11

*asked on July 30, 2010* -
## calculus

Time (months) 0 1 2 3 4 5 Rate pollutants are escaping 2 5 7 16 24 34 Use this data to sketch a graph Draw rectangles on this graph (as in Figure 5.2) to help you underestimate the total pollutants that escaped during the first month. What underestimate

*asked on November 7, 2010* -
## math

3.6 is 12% of what number?

*asked on January 11, 2016* -
## chemistry

What is the chemical equation that describes the complete neutralization of H3PO4 by NaOH? A. H3PO4 + 2NaOH Na2HPO4 + 2H2O B. H3PO4 + H2O H2PO4- + H3O+ C. H3PO4 + NaOH NaH2PO4 + H2O D. H3PO4 + 3NaOH Na3PO4 + 3H2O

*asked on September 14, 2016* -
## college chemistry

For the equilibrium Br2 + Cl2 goes to 2BrCl at 400 K ,Kc = 7.0. 0.30 of Br2 and 0.30 of Cl2 are introduced into a 1.0 L- container at 400 K.a) What will be the equilibrium concentration of Br2? b) What will be the equilibrium concentration of Cl2 ? c) What

*asked on October 7, 2011* -
## Algebra

What are the equivalent fraction and decimal for 33 1/3%? A. 1/33 and 0.3 B. 1/33 and 3 C. 3 1/3 and 0.333333 D. 1/33 and 0.333333

*asked on November 28, 2016* -
## economics

Suppose that bicycles are produced by a perfectly competitive, constant cost industry. Which of the following will have a larger effect on the long-run price of bicycles: (1) a government program to advertise the health benefits of bicycling, or (2) a

*asked on November 7, 2011* -
## chemistry

How many grams do 6.2×1024 atoms of argon weigh? Answer in units of g.

*asked on January 10, 2016* -
## chemistry

How many grams of calcium oxide, CaO, can be produced from 4.20 g of calcium metal and 1.60 g of oxygen gas?

*asked on September 21, 2008* -
## Physics

A student standing on the ground throws a ball straight up. The ball leaves the student's hand with a speed of 17.0 m/s when the hand is 1.50 m above the ground. How long is the ball in the air before it hits the ground? (The student moves her hand out of

*asked on September 17, 2015* -
## math

maria throws a ball straight up with an initial velocity of 10m/s what is its velocity at the highest point?

*asked on March 10, 2015* -
## chemistry

The equilibrium constant for the formation of phosphorus pentachloride is 1.9. If the partial pressure of each gas is 0.5 atm, will the reaction (as written) proceed forward or backward to reach equilibrium? PCl3(g) + Cl2(g) PCl5(g) A. Backward, because K

*asked on September 15, 2016* -
## chemistry

Write a balanced equation for the double-replacement precipitation reaction described, using the smallest possible integer coefficients. A precipitate forms when aqueous solutions of iron(II) iodide and sodium hydroxide are combined.

*asked on November 4, 2016* -
## math help please

Miranda baked 48 muffins to sell at the school bake sale. She sold 2/3 of the muffins and gave the rest to her friends to eat. How many muffins did she sell?

*asked on January 12, 2016* -
## physics

A group of hikers hears an echo 2.50 s after shouting. If the temperature is 20.0°C, how far away is the mountain that reflected the sound wave?

*asked on April 24, 2013* -
## Math

Three boxes each contain a number of billiard balls. One box contains only even-numbered balls, one box contains only odd numbered billiard balls, and the third box contains a mixture of odd and even numbered balls. All the boxes are mislabeled. By

*asked on February 17, 2015* -
## college chemistry

Calculate the equilibrium concentration of H3O+ in the solution if the initial concentration of C6H5COOH is 6.0×10^-2. Kc=6.3 *10^-5

*asked on October 20, 2011* -
## chemistry

The shape of H3C+ is best described as?

*asked on October 3, 2008* -
## Chemistry

how many moles of Cl in 2.7 mol CaCl2

*asked on September 25, 2012* -
## chemistry

Knowing what information would allow you to order gas molecules according to their velocity? A. Pressure and temperature B. Volume and molecular mass C. Pressure and volume D. Temperature and molecular mass

*asked on September 14, 2016* -
## Chemistry

Sulfur burns in oxygen in two steps: i.S(s) + O2(g) ->SO2(g) change of Heat=-297kJ ii. 2SO2(g) + O2(g)->2SO3(g) change of heat=-198kJ Calculate the total heat released if this is the final reaction: 2S(s) + 3O2(g)->2SO3(g)

*asked on April 6, 2011* -
## math

Suppose you deposit $275.00 in your savings account on December 31. Your bank pays 3 percent annual interest on savings accounts. If you do not deposit any more money into the account, what would be the balance on December 31 of the following year?

*asked on September 24, 2017* -
## chemistry - 3.1.6

At a high temperature, the equilibrium constant for the decomposition of hydrogen iodide is 65.0. If the initial concentration of HI is 1.60 M, what is the concentration of hydrogen at equilibrium? 2Hl(g) H2(g) + I2(g) A. 1.42 M B. 0.753 M C. 0.240 M D.

*asked on September 15, 2016* -
## Calculus

find the parabola whose minimum is at (7,6) rather than the point given in the book. The parabola's equation is y = x2 + ax + b, where a = and b =

*asked on October 27, 2010* -
## Equal riddle

I am between 20 to 30.when u put me into 5 equal group, there is an odd number in each group and one is left over.what number am i

*asked on September 12, 2017* -
## chemistry

How does table salt (NaCl) dissolve in water? A. Water molecules hydrogen bond with sodium ions and chloride ions. B. Each sodium ion is surrounded by chloride ions. C. Each NaCl molecule is surrounded by water molecules. D. The oxygen atoms in water

*asked on September 14, 2016* -
## 8th Grade Algebra

I need help with these problems: 1) A vending machine takes only nickels and dimes. There are 5 times as many dimes as nickels in the machine. The face value of the coins is $4.40. How many of each coin are in the machine? 2) A vending machine takes only

*asked on March 3, 2009* -
## chemistry

Given the reaction: Cu2+(aq) + S2-(aq) CuS(s) What will happen (a) if CuSO4(aq) is added? And (b) if Na2SO4(aq) is added? A. (a) Nothing; (b) Less product will form B. (a) Less product will form; (b) Nothing C. (a) Nothing; (b) More product will form D.

*asked on September 15, 2016* -
## geometry

The angle of depression from the top of a lighthouse to a boat in the water is 30°. If the lighthouse is 89 feet tall how far is the boat from the lighthouse to the nearest foot? Answers available in ... 10Take this time to do your best on this question.

*asked on February 12, 2013* -
## Math

Find all pairs of integers such that when they are added they equal 100, and when they are multiplied they are at least 2000.

*asked on February 10, 2015* -
## math

Two different relationships are shown below. Relationship 1: xy = 3 Relationship 2: A graph is shown that has the following points plotted: one comma three, two comma six, three comma nine, four comma twelve. a) Identify each relationship as direct or

*asked on April 16, 2013* -
## chemistry

How many molecules are in 24.0 g NO2? Answer in units of molec.

*asked on January 10, 2016* -
## chemistry

Why does the density of gas in a hot air balloon decrease as the gas is heated? A. The mass of gas decreases as temperature increases. B. The mass of gas increases as temperature increases. C. The volume of gas decreases as temperature increases. D. The

*asked on September 14, 2016* -
## Science

Is rubbing alcohol a pure substance or a mixture?

*asked on September 26, 2010* -
## chemistry

The binding energy of an electron to a metal surface is 184 kJ/mol. What is the threshold wavelength (in nm) for the onset of the photoelextric effect?

*asked on September 21, 2008* -
## Calculus

Sinx=e^y , 0

*asked on December 5, 2016* -
## Social Studies

Name two other factors besides latitude that influence japans climate? and what major ocean currents affect japan

*asked on April 14, 2011* -
## cal

find the equation of a quadratic function whose graph is tangent at x=1 to the line whose slope8, tangent at x=-2 to solve the line with slope-4 and tangent to the line y=-8 find the equation of the tangent lines at x=1 and x=-2 graph the quadratic

*asked on February 28, 2011* -
## chemistry

An aqueous solution of silver nitrate contains 5.00 g of silver nitrate. To this solution is added sufficient barium chloride to precipitate all the silver as silver chloride. What mass, in grams, of dry silver chloride can be obtained?

*asked on September 21, 2008* -
## earth

How do Plate tectonics affect the Atmosphere, Hydrosphere, Geosphere, and Biosphere? Thanks SO much in advance!:D

*asked on March 15, 2012* -
## Physics

Your new designer chair has an S-shaped tubular metal frame that behaves just like a spring with the spring constant 13500 N/m. When your friend, who weighs 910 N, sits on the chair, how far does it bend?

*asked on September 26, 2014* -
## Physics

The range of human hearing extends from approximately 20 Hz to 20,000 Hz. Find the wavelengths of these extremes at a temperature of 26°C. -Find wavelengths fron 20 hz: -Find wavelengths for 20,000 hz:

*asked on April 24, 2013* -
## chemistry

Given the following reaction: 4 KO2 + 2 H2O + 4 CO2 4 KHCO3 + 3 O2 How many moles of H2O are needed to react with 12.15 moles of CO2? moles A chemical reaction occurs between solutions of LiCl and silver nitrate. This reaction produces a precipitate that

*asked on October 22, 2010* -
## 6th grade

tHE AREA OF A RECTANGLE IS 24CM2 IF THE LENGTH OF THE SIDES ARE WHOLE NUMBERS WHICH OF THE FOLLOWING WOULD NOT BE POSSIBLE .EXPLAIN A:16CM,8CM B:12CM,2CM C:6CM,4CM D:3CM,8CM,

*asked on April 28, 2009* -
## math

how could you use the product 108 and 4 to find the product of 324 and 4?

*asked on October 13, 2008* -
## chemistry

What is the total number of nonbonding valence electrons in the "dipolar ion" form of glycine, +NH3CH2COO-?

*asked on October 3, 2008* -
## math

Jorge sees that there are small and large squares in the tile design belo.how many squares are there in all in the design?

*asked on March 20, 2014* -
## chemistry

What effect does raising the temperature of the reaction chamber at a constant pressure have on the following reaction at equilibrium? 2NO2(g) N2O4(g) + heat A. The equilibrium shifts toward the reactants because the reverse reaction is endothermic. B. The

*asked on September 15, 2016* -
## chemistry

How many molecules are in 0.0700 mol NH3? Answer in units of molec.

*asked on January 10, 2016* -
## Math

Im just a little confused on how to answer this question. A ball bounced 64% of the height from which it was dropped. The bounce was 72 cm high. What is the height from which the ball was dropped. I think there has to be an algebraic equation of some sort,

*asked on May 15, 2011* -
## Chemistry

Which of the following ions is paramagnetic in the ground state: Na+ Zn+2 Ti+2 Sr+2

*asked on April 8, 2011* -
## algebra

a steamboat travels 9 miles up a river in 3 hours and returns the same distance down the river in 2 hours. find the speed of the boat in still water and the rate of the current.

*asked on February 4, 2012* -
## Science

What does a sharp shadow tell us about the way light travels?

*asked on March 2, 2011* -
## physiology

You are a physiologist on a space flight to a distant planet. You discover aliens inhabiting the planet and they are willing to submit to your tests. You discover that the aliens kidney handles the sugar alcohol mannitol just like our kidneys handle

*asked on November 19, 2008* -
## civics

explain two weaknesses of the Articles of Confederation

*asked on December 4, 2007* -
## chemistry

How many molecules are contained in 1.30 mol O2? Answer in units of molec.

*asked on January 10, 2016* -
## Calculus

fter a foreign substance is introduced into the blood, the rate at which antibodies are made is modeled by f(t) = 27 t/8 t^2 + 3 where f(t) is in thousands of antibodies per minute, and t is measured in minutes with 0 ≤ t ≤ 60. Assuming that there are

*asked on November 12, 2010* -
## chemistry -3.2.4

Given the reaction: Cu2+(aq) + S2-(aq) CuS(s) What will happen (a) if CuSO4(aq) is added? And (b) if Na2SO4(aq) is added? A. (a) Nothing; (b) Less product will form B. (a) Less product will form; (b) Nothing C. (a) Nothing; (b) More product will form D.

*asked on September 15, 2016* -
## Calculus

N(t) = 650/1+649 e^−0.5 t (b) How many people will have heard the rumor after 4 hours? After 9 hours? (c) When will half the people have heard the rumor? t = (d) When is the rumor spreading fastest? t =

*asked on November 5, 2010* -
## chemistry

How can you shift the equilibrium of the reaction between hydrogen and chlorine toward the products? H2(g) + Cl2(g) --> 2HCl(g) A. Add Cl2. B. Remove H2. C. Increase the pressure. D. Add HCl. would the answer to this one be to add Cl2? so answer A?

*asked on September 15, 2016* -
## SCience

whyis frosted glass often used for bathroom windows instead of clear glass or solid wall?

*asked on March 2, 2011* -
## College Chemistry

Given 20 mL NaOH; 0.1 M, add 0.05 M HCl, 10 mL at a time. What is the pH initially of NaOH? What is the pH after adding 10 mL 0.05 M HCl? What is the pH after adding 20 mL 0.05 M HCl? What is the pH after adding 30 mL 0.05 M HCl? What is the pH after

*asked on July 7, 2010* -
## civics

why was the ratification of Virginia important to the constitution?

*asked on December 5, 2007* -
## math

PLEASE TELL ME THE ANSWER TO "blank 569 divided by 6 is about 400!!!!!!!!" WHAT IS THE BLANK?!!?!?!?

*asked on February 23, 2017* -
## algebra

the winninq three-digit number in a drawing for a door prize had the same units and hundreds digit. the product of its units and tens digits was 5 less than twice the sum of its digits. its middle digit was one more than twice its units digit. What was the

*asked on February 4, 2012* -
## algebra

brendan mixed cola and cherry juice to make a party drink. for each 16-ounce can of cola, he used one ounce of cherry juice. if he made 17 quarts of party drink, how many cans of cola did he used, and how many ounces of cherry juice did he need?

*asked on February 4, 2012* -
## calculus

find the equation of a quadratic function whose graph is tangent at x=1 to the line whose slope8, tangent at x=-2 to solve the line with slope-4 and tangent to the line y=-8

*asked on February 28, 2011* -
## math help

Hank rode his motorcycle half the distance from Lumberton to Wilmington, which are 70 miles apart. How many miles did he ride?

*asked on January 12, 2016* -
## Physics

You swing a 2.40kg stone in a circle, using the full length of a thin 60.0cm rope.

*asked on November 1, 2014* -
## Math

It takes pipe A 14 days to fill the fish pond. It takes pipe B 18 days to fill the same pond. Find out how pond it takes both pipes working together to fill the pond

*asked on May 20, 2013* -
## Physics

A sound wave has a frequency of 686 Hz in air and a wavelength of 0.50 m. What is the temperature of the air?

*asked on April 24, 2013* -
## Calculus

Year 1960 1970 1980 1990 2000 Rate 39 59 64 89 106 of change (million people per year) Use this data to sketch a graph like that in Figure 5.2 on page 238. Draw rectangles on this graph (as in Figure 5.2) to help you underestimate the total change in the

*asked on November 7, 2010* -
## chem

Using the equation 2H2 + O2 ==> 2H2O, determine how many grams of water is produced when 29 moles of oxygen is consumed

*asked on January 24, 2017* -
## chem

Using the equation 2H2 + O2 ==> 2H2O, determine how many grams of water is produced when 29 moles of oxygen is consumed

*asked on January 24, 2017* -
## HELP! Physics

A heat engine operates between two reservoirs at temperatures of 19.7oC and 294oC. What is the maximum efficiency possible for this engine?

*asked on November 16, 2012* -
## Grade 9 Chemistry (2)

What is one way in which Noble Gases are different from other elements? a. Noble Gases have low boiling points b. Noble gases have high melting points c. Noble gases have extremely high densities d. Noble gases have unusually high atomic masses Also, what

*asked on June 20, 2012* -
## physics

you drive a car for 2.0 h at 40km/h, then for another 2.0 h at 60km/h. what is your average velocity?

*asked on February 4, 2012* -
## algebra

the perimeter of a rectangular field is 172 meters. double the width is 4 meters more than the length. find the area of the field.

*asked on February 4, 2012*