1. ## Gaussian elimination

Hi,

Q1. Fit a quadratic polynomial to the points (1,4), (3,8), (-2,8) by writing the general equation, setting up and solving a system of 3 linear equations.

Use technology to graph the polynomial over the interval x = -4 to x = 4. Add the given points to confirm that the curve you found is correct, by hand.

ok i understand this question, i subbed in the points and ended up with 3 equations, thus leading to the gaussian elimination matrix:

4 = a + b + c
8 = 9a + 3b + c
8 = 4a - 2b + c

through the steps i got the answer C = 41, b = -9, a = -2/5

it was rough, is this correct?

thanks

moon

2. Originally Posted by Moon Hoplite
Hi,

Q1. Fit a quadratic polynomial to the points (1,4), (3,8), (-2,8) by writing the general equation, setting up and solving a system of 3 linear equations.

Use technology to graph the polynomial over the interval x = -4 to x = 4. Add the given points to confirm that the curve you found is correct, by hand.

ok i understand this question, i subbed in the points and ended up with 3 equations, thus leading to the gaussian elimination matrix:

4 = a + b + c
8 = 9a + 3b + c
8 = 4a - 2b + c

through the steps i got the answer C = 41, b = -9, a = -2/5

it was rough, is this correct?

thanks

moon
No. You can check your answers in a guassian elimination by subbing them back into the original equations to see if they are satisfied. The first of your equations is not satisfied by your solutions.