Quadratic help please.

Question

Write the function of the form y = ax^2 + bx + c whose graph passes through the three given points: (1, 2), (0, 4), (–1, 4).

Answer 1

hlere's how to do this:

substitute the x & y from given point # 1; this makes an equation involving a, b, c.

repeat using given point #2--another equation...

repeat using given point # 3---Result: 3 equations in the three unknowns a, b, c.

 

You can solve this system by Elimination/Substitution methods (can be tedious), or by using determinants (Cramer's rule) or b y Reduced Row Echelon methodology, either manually or on calculator (TI-84's RREF FUNCTION operating on an augmented 3 by 4 matrix).