# Posts by katie

Total # Posts: 2,096

**History PLZ HELP ASAP!!!**

1. C they walked from Asia to North America over a strip of land that since been covered by the ocean 2. A and c 3. B and c 100% correct

**precalc**

I don't see how an eigenvalue calculator helps me with #1 and the first part of #2. I also don't know what you mean by "there should be a proof in your text. The discussion about eigenvectors will show that they are a basis for the vector space." Thanks!~

**precalc**

Given a square matrix M, we say that a nonzero vector v is an eigenvector of M if Mv=kv for some real number k. The real number k is called the eigenvalue of v with respect to M. 1. Let v be an eigenvector of the matrix M with eigenvalue k. Find a simple expression for (M^n)v...

**chemistry assignment**

(a): You can do that. (b), (c), and (d): Google "accuracy vs. precision" and I think that will help you get on the right track.

**Analytical Chemistry**

I was able to solve it! Thank you again Dr.Bob! This is the 2nd time you've saved me this semester! I greatly appreciate it! :D

**Analytical Chemistry**

I was able to do Equation 2 and got 1.58 for b/a ...

**Analytical Chemistry**

This question pertaining to buffer systems! How would you prepare 10.0mL of 0.0100M phosphate buffer, pH = 7.4 0, from stock solution of 0.100M KH2PO4 and 0.250M K2HPO4, pKa of KH2PO4 is 7.20. Please help me in figuring out how I even start this problem...as well as attempting...

**Chemistry**

The following soluble salts are strong electrolytes. For each, write a balanced equation for their dissociation in water. NaBr BaBr2 Li3PO4

**Chemistry Theory**

We are able to "see" the shapes of molecules with X-ray crystallography. However, even without this technology, there is a great deal of evidence that water, H2O, is a bent, polar molecule. Discuss this evidence and explain how it relates to our model of the water ...

**Analytical Chemistry**

@ Dr.Bob222 Thank you for the help! it is greatly appreciated! However - Do I graph the last number saying Sample and 0.310? Or is that not necessary?

**Analytical Chemistry**

I am having major issues with this problem and I no clue where to start. It also doesn't help that the professor never taught us how to calculate mass % from data like this... Students in the analytical chemistry class were given a sample of spinach to determine its iron ...

**Precalc**

Rhombus ABCD, with side length 6, is rolled to form a cylinder of volume 6 by taping side AB to side DC. What is sin(angle ABC)?

**precalc**

Points A, B, and C are on the circumference of a circle with radius 2 such that angle BAC = 45 degrees and angle ACB = 60 degrees. Find the area of triangle ABC.

**Math**

Use the value sin x = 1/ 2 and cos x > 0 to find the values of all six trigonometric functions. Leave your answer in exact form, not in decimal

**Physics**

I've looked at other questions posted like this and can't understand the problem or any of the answers. Could someone please show how to find for Cliff and Will? Cliff and Will are carrying a uniform 2.0m board of mass 75kg. Will is supporting the board at the end ...

**Probability**

Brenda’s Bike Booth, at the mall, allows people to order a bike in their choice of 4 colors (Atomic Tangerine, Banana, Café Noir, or Dollar Bill) and the options of with or without a basket; with or without a horn. Given all of these options, what’s the ...

**Probability :(**

Brenda’s Bike Booth, at the mall, allows people to order a bike in their choice of 4 colors (Atomic Tangerine, Banana, Café Noir, or Dollar Bill) and the options of with or without a basket; with or without a horn. Given all of these options, what’s the ...

**Algebra**

The difference of two numbers is 96 and their sum is 300. Find the numbers. What is the answer for that?

**math**

Angle = 20 Complement = 70 Supplement = 160

**Precalc**

Let x and y be real numbers such that x^2 + y^2 = 1. Find the max value of 2x - 5y. A hint was given to use Cauchy-Schwarz but I'm not sure how to apply it to vectors?

**Math**

Let a, b, and c be unit vectors, such that a+b+c=0. Show that the angle between any two of these vectors is 120 degrees. I proved this geometrically, but now my teacher wants a proof using vectors, and I don't know what to do.

**math**

How do you find P3, P13, and P15? P10 is obviously (-1, 0), but I'm not sure how you got P2 and how to find the other three points

**math**

Let P_1 P_2 ... P_18 be a regular 18-gon. Show that P_1 P_10, P_2 P_13, P_3 P_15 are concurrent. I've proved this with a diagram, but the question requires a rigorous proof.

**Math**

Suppose p and q are points on the unit circle such that the line through p and q intersects the real axis. Show if z is the point where this line intersects the real axis, then z=(p+q)/(pq+1) So far I've figured out that the equation for the line is z=p+t(q-p) but I don&#...

**math**

You deposit $400 in a savings account that earns 7% interest compounded annually. What is the function that represents your balance after t years?

**math**

Find the imaginary part of (cos(12) + i sin(12) + cos(48) + i sin(48))^6.

**Math**

Please help me with this ASAP! I need help with this just checking my answers thanks 1. There are 14 blue marbles, 8red marbles, and 12 green marbles in a jar. What is the ratio of the total number of marbles to the number of red marbles? A. 24:8 B. 34:8 (my answer) C. 8:34 D...

**Chemistry**

In a hydrogen- oxygen fuel cell hydrogen diffuses through the cathode. hydrogen and oxygen are mixed before entering the anode.*** oxygen diffuses through the anode. oxygen diffuses through the cathode.

**Chemistry**

To charge a lead storage battery you must apply a direct current to it. hold a magnet close to it.*** force alternating current through it. increase the pressure on it.

**ALGEBRA**

Rodney fa fair coin and chooses a ter tiles A, E, I, O AND U. He performs this experiment 50 times to determine the experimental probability that heds is tossed and the letter A is chosen. Whitch o following is st likely to be the experimental probability that Rodney ...

**Math**

If w^3 = 1 and w != 1, then compute (1 - w + w^2)(1 + w - w^2).

**Math**

Mike drank more than half te juice in his glass. What fraction of the juice could mike have drunk.

**science**

If Faraday hd used a more powerful battery in his experiments with electromagnetic induction, what affect would this have had on his galvanometer's measurements of current when the battery was fully connected? explain your reasoning. Thanks again!

**science**

Describe how turning off the electric current in an industrial magnet affects its magnetic field. Thanks!

**Math**

And yes I saw this problem on stackexchange but the solution was not very good at explaining it and only gave the math, which is really hard to understand

**Math**

Let z be a complex number, and let n be a positive integer such that z^n = (z + 1)^n = 1. Prove that n is divisible by 6. I have no idea how to approach this problem!

**science**

Lesson 9: Energy and the Environment Unit Test Science 7 B Unit 3: Energy and the Environment does anyone have answers to this text C.A

**Complex Numbers**

Let z and w be complex numbers such that |z| = |w| = 1, and zw is not equal to -1. Prove that (z + w)/(zw + 1) is a real number.

**Precalculus**

Let z and w be complex numbers such that |z| = |w| = 1, and zw is not equal to -1. Prove that (z + w)/(zw + 1) is a real number.

**Math**

Let z and w be complex numbers such that |z| = |w| = 1, and zw is not equal to -1. Prove that (z + w)/(zw + 1) is a real number.

**Complex Numbers**

Let z and w be complex numbers such that |z| = |w| = 1, and zw is not equal to -1. Prove that (z + w)/(zw + 1) is a real number.

**Polar, Cylindrical, and Spherical Coordinates**

Never mind, I think I get it now

**Polar, Cylindrical, and Spherical Coordinates**

Sorry, they just seem unclear, and you seem unsure of your final answer... And I didn't think you would respond to the original thread so I resposted

**Polar, Cylindrical, and Spherical Coordinates**

Let C be a circle that passes through the origin. Show that we can find real numbers s and t such that C is the graph of r = 2s*cos(theta + t) I think that I could start by writing it like R^2=(x-h)^2+(y-k)^2 where R is the radius of the circle, but I don't what to do with...

**math**

Find the probability of the following event: tossing a coin heads up or rolling a 3 with a number cube. I got: 1/2+1/6 = 2/3 but the right answer is 7/12. I don't understand how to get 7/12. Please help.

**Math**

tossing a coin tails up or rolling a number less than 4 on a number cube. I got 1/2 + 3/6 and got 1. The answer is 3/4. I don't understand what to do. Please help.

**Precalculus**

Let C be a circle that passes through the origin. Show that we can find real numbers s and t such that C is the graph of r = 2s*cos(theta + t) I think that I could start by writing it like R^2=(x-h)^2+(y-k)^2 where R is the radius of the circle, but I don't what to do with...

**Math**

Find the probability of the following event: tossing a coin tails up or rolling a number less than 4 on a number cube. I got 1/2 + 3/6 and got 1. The answer is 3/4. I don't understand what to do. Please help.

**Math**

Find the probability of the following event: tossing a coin heads up or rolling a 3 with a number cube. I got: 1/2+1/6 = 2/3 but the right answer is 7/12. I don't understand how to get 7/12. Please help.

**Math--Parametric Equations**

A hockey puck of diameter 3 inches is spinning around its center at a speed of 3 counterclockwise rotations per second. The center of the puck is traveling at a speed of 24 inches per second at an angle of 45 degrees to the positive x-axis. (a) At time t=0, the center of the ...

**Social Studies**

Are these right?

**Math: Trigonometry**

Find the sum of the three smallest positive values of x such that 4cos^2(2x-pi) = 3. (Answer in radians.)

**Math: Parametric Equations**

The graph of the parametric equations x=cos(t) y=sin(t) meets the graph of the parametric equations x=2+4cos(s) y=3+4sin(s) at two points. Find the slope of the line between these two points. So far I've set up the system of equations cos(t)=2+4cos(s) sin(t)=3+4sin(s) but ...

**Calculus**

An energy drink container in the shape of a right circular cylinder must have a volume of 12 fluid ounces (1 fluid ounce is approximately 1.80469 cubic inches). The cost per square inch of constructing the top and bottom is twice the cost of constructing the lateral side. Find...

**Math: Parametric Equations**

But that wouldn't be the right answer since it's asking for a length.

**Math: Parametric Equations**

So would the interval be (-inf, 1] ??

**Math: Parametric Equations**

Let G be the graph of the parametric equations x = cos(4t), y = sin(6t). What is the length of the smallest interval P such that the graph of these equations for all t E P produces the entire graph G? (The "E" represents the symbol for "is in" that looks ...

**Precalculus**

Oh I see! Yes, your answer is correct Reiny. Thanks!

**Precalculus**

Hmm 326 is not right... I'm also confused on "circumference = 8 (360/45) = 64 = 2 pi r" can you explain that a bit?

**Precalculus**

Points A, B, and C are on a circle such that angle ABC=45 degrees, AB=6, and AC=8. Find the area of the circle.

**Math: Trigonometry**

Does that mean there's 16 values of n?

**Math: Trigonometry**

For how many values of n with 0<=n<=100 is the graph of f(x) = sin(x + n) identical to the graph of g(x) = cos(x)? I think that I should use the relationship that cos(x)=sin(90-x) but I'm not sure how.

**Trigonometry**

For how many values of x such that 0<x<360 do we have cos(x) = 0.1? (x is in radians)

**Trigonometry**

If sin(x) = 4cos(x), then what is (sin(x))*(cos (x))?

**Math**

You order a pizza. The pizza has a diameter of 14 inches and it is cut into 12 equal slices. You eat four slices, how much of the area have you consumed. How long is the remaining crust.

**English**

Its on "Lamb to the Slaughter" and "Royal Jelly", both by Roald Dahl.

**English**

Would someone be willing to grade or check my rough draft of a critical review?

**Algebra**

Find ALL triples of positive numbers c<100 that satisfy the Pythagorean Theorem.

**biology**

what type of cell recognizes cells that have been infected by viruses because the infected cells have viral proteins on their surfaces?

**geometry**

an inscribed angle with a diameter as a side has a measure of x degrees. if the ratio of measure of arc AD to measure of arc DB is 1:4, what is the measure of arc DB?

**geometry**

A painter sets a ladder up to reach the bottom of a second-story window 16 feet above the ground. The base of the ladder is 12 feet from the house. While the painter mixes the paint, a neighbor's dog bumps the ladder, which moves the base 2 feet farther away from the house...

**Algebra**

No, not in calculus yet - I will take that next. Thank you so much for your help!

**Algebra**

A rectangular playground is to be fenced off and divided in two by another fence parallel to one side of the playground. 440 feet of fencing is used. Find the dimensions of the playground that maximize the total enclosed area. Remember to reduce any fractions and simplify your...

**science**

Yeah it's C 100%

**Pre-Calc**

Solve the quadratic equation by factoring. Check your solutions in the original equation. (Enter your answers as a comma-separated list.) x^2 + 2ax + a^2 = 0

**Math**

An open gift box is to be made from a square piece of material by cutting four-centimeter squares from each corner and turning up the sides (see figure). The volume of the finished gift box is to be 324 cubic centimeters. Find the size of the original piece of material.

**Pre-Calc**

An open gift box is to be made from a square piece of material by cutting four-centimeter squares from each corner and turning up the sides (see figure). The volume of the finished gift box is to be 324 cubic centimeters. Find the size of the original piece of material.

**nursing**

1 L is to infuse every 12 hours. calculate the mL/hr

**Math**

Never mind. My mom helped me.

**Math**

Which equation has a slope of -1/2 and a y intercept of -3? a. 4x+2y+3=0 b. 3x+6y+6=0 c. 5x +10y+30=0 d. 6x+2y+1=0 I have the answer. I know it is C, but this was today's lesson and I still don't understand why or how to get C. Please help.

**math**

the product of y and six exceeds three times the sum of y and four

**Chemistry**

Kc = 28 at some temperature for the reaction H2(g) + I2(g) ⇀↽ 2 HI(g). If 16.7 moles of HI are introduced into a 10.0 liter vessel, how many moles of I2 are present at equilibrium? Answer in units of mol.

**Chemistry**

The heat of vaporization of water is 9.73 kcal/mol. At what pressure (in torr) would pure water boil at 89◦C?

**Math Please check**

(1/8)17n x 8 I got: 17n/8 x 8= 17n not sure about this??

**Math**

Yes that's what I meant. Thank you

**Math**

4s-(3-2s)-6=9 Please check my work: 4s-3+2s-6=9 6s-9=9 3s=18 s=3

**math**

The probability of drawing a red coin after three blue coins are put in the bag to replace the red one that has been removed is

**Math**

Could you please explain the differences between linear relationships and exponential relationships? How or when would I use either or them? Thank you.

**Math**

The area of a rectangle is 12 square feet. What are all the possible integer values of its perimeter? I got: 1. all sides equal to 3 2. 5, 5, 1, 1 3. 4,4,2,2 Did I miss any combinations?

**Math**

A rollercoaster travels at 120 miles per hour on its track for 3 minutes. A. 3 minutes is what part of an hour? B Use a formula and your answer from above to calculate the distance traveled. A. I got 1/20 or 5% B. Not sure what formula to use. But I got .40 of a mile What do ...

**Math**

Got it now! Thank you!

**Math**

49^2 is 2,401 is that the area of the tablecloth? The back of my book has the answer as 2704, did I forget to do something?

**Math**

A square table has an area of 2116 square inches. A tablecloth hangs 3 inches over each end of the table. a. What is the length of one side of the table? b.What is the area of the tablecloth? a. I know is 46 inches Please help me to figure out b. Thank you.

**Algebra**

Thank you!

**Algebra**

I just need help setting up the equation - the rest I can do on my own: A man built a walk of uniform width around a rectangular pool. If the area of the walk is 253 square feet and the dimensions of the pool are 9 feet by 3 feet, how wide is the walk?

**language Arts**

In the excerpt from Barrio Boy, what makes Ernesto similar to several of his classmates?

**English**

Thanks James :)

**English**

THANK YOU AUSTRALLIAN DUDE! OMG I GOT THEM ALL RIGHT (Exept for one but that's okay your awesome 16 was really theirs.) Thanks again!! :)))

**Math**

A can containing 3 tennis balls has a volume of 128/9pi cubic inches. If the height of the cylinder is 8in., what is the diameter of each tennis ball. Please explain how to do this.

**Math**

Mary bought a roll of ribbon. After using 5/8 of the ribbon to decorate some packages she had 15ft left how many feet of ribbon did she buy