Hello, trythis!

Fit a quadratic polynomial to the points (1,4), (3,8), (-2,8)

by writing the general equation, setting up and solving of 3 linear equations.

how to solve using row-reduce method?

The general quadatic is: .

Those three points must satisfy the equation, so we have:

. .

Then we have the augmented matrix: .

. . and I assume you know how to row-reduce it . . .