Calculus/Max/min

Advertisement

Expert: - 2/21/2011


Question
I'm trying to find the point (x,y,z) on the plane 2x-y+z=3 that is closest to the point (2,0,-1).

I used method of elimination of variables, and got the point to be (-5/7 , 18/7, 13/7)

where:
x = -5/7
y = 18/7
z = 13/7

Is this the correct answer?

Answer
No, since 2(-5/7) - 18/7 + 13/7 = -15/7, whereas it should equal 3, which is 21/7.

From what I can see, (2,0,-1) is on the plane defined by 2x - y + z = 3,
for 2(2) - 0 + -1 = 3 - 1 = 3, and that's what the equation says it should be to be on the plain.

Using this, the point that is closest to (2,0,-1) and on the plane is the point itself.

Calculus

All Answers

Answers by Expert:

Ask Experts

Volunteer

Scotto

Expertise

Any kind of calculus question you want. I also have answered some questions in Physics (mass, momentum, falling bodies), Chemistry (charge, reactions, symbols, molecules), and Biology.

Experience

Experience in the area: I have tutored students in all areas of mathematics for over 25 years. Education/Credentials: BSand MS in Mathematics from Oregon State University, where I completed sophomore course in Physics and Chemistry. I received both degrees with high honors. Awards and Honors: I have passed Actuarial tests 100, 110, and 135.

Publications
Maybe not a publication, but I have respond to well oveer 7,500 questions on the PC. Well over 2,000 of them have been in calculus.

Education/Credentials
I aquired well over 40 hours of upper division courses. This was well over the number that were required. I graduated with honors in both my BS and MS degree from Oregon State University. I was allowed to jump into a few junior level courses my sophomore year.

Awards and Honors
I have been nominated as the expert of the month several times. All of my scores right now are at least a 9.8 average (out of 10).

Past/Present Clients
My past clients have been students at OSU, students at the college in South Seattle, referals from a company, friends and aquantenances, people from my church, and people like you from all over the world.

©2012 About.com, a part of The New York Times Company. All rights reserved.