Beginner's linear algebra question

AI Thread Summary
A beginner in a linear algebra course is struggling with formulating and solving systems of linear equations to find polynomial coefficients. The discussion includes two examples: finding a linear function for two points and a polynomial for four points. Participants provide hints on how to set up equations based on known coordinates to solve for unknown coefficients. The original poster expresses frustration but ultimately finds clarity through the guidance offered. The conversation emphasizes the importance of understanding the relationship between points and polynomial equations in linear algebra.
lezardo
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Hi everyone! I recently started taking a basic linear algebra course at my university and I'm already having problems. I used to be pretty good at math in general, but I guess I've unlearned everything over the years. Any help would be appreciated, thanks!

A.
Two points on a plane with the coordinates (x0,y0) and (x1,y1) define a graph with the form:
y = c1x + c0 (polynomial of the 1. degree).

1)Formulate a system of linear equations to find the coefficients of this function.
2) Solve this system of equations to find the function which runs through the points (1;3) and (2;4).


B.
n + 1 points on a plane [(x0, y0), (x1, y1),…; (xn, yn)] define a polynomial of the nth degree:
y = cnx^n + …+ c2x^2 + c1x + c0.

1)Formulate a system of linear equations to find the coefficients of this polynomial.
2) Solve this system to find the polynomial which runs through the points (0;1), (1;10), (2,33) and (3,64).


P.S. Hints or something like that would also be great. It's really frustrating sitting here with nothing but "duhhhhh" in my head.
 
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Do you understand the question? It's asking you to find the equation of the polynomial whose graph passes through those points. Here is a hint on part A. The equation you are trying to find is y = c1x + c0 (you are trying to find the c's). You know that the point (x0, y0) satisfies this equation and so does (x1, y1). So you can write, for example
y0 = c1x0 + c0
where y0 and x0 are KNOWN and c1 and c0 are UNKNOWN.
Can you figure it out now?
 
Do you understand the question? It's asking you to find the equation of the polynomial whose graph passes through those points. Here is a hint on part A. The equation you are trying to find is y = c1x + c0 (you are trying to find the c's). You know that the point (x0, y0) satisfies this equation and so does (x1, y1). So you can write, for example
y0 = c1x0 + c0
where y0 and x0 are KNOWN and c1 and c0 are UNKNOWN.
Can you figure it out now?

Well, i feel stupid. It was staring me right in the face. Thanks a lot!
 
I picked up this problem from the Schaum's series book titled "College Mathematics" by Ayres/Schmidt. It is a solved problem in the book. But what surprised me was that the solution to this problem was given in one line without any explanation. I could, therefore, not understand how the given one-line solution was reached. The one-line solution in the book says: The equation is ##x \cos{\omega} +y \sin{\omega} - 5 = 0##, ##\omega## being the parameter. From my side, the only thing I could...

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