Evaluating Quadratic Functions (5.5) Figuring out values for y given x Figuring out values for x given y
First a little POD What is the complex conjugate of i? What is their product? What is the complex conjugate of m + ni? What is their product?
For f(x) = 3x 2 + 2x -11 Find f(-4). Find the x-intercepts.
For f(x) = 3x 2 + 2x -11 f(-4) = 3(-4) 2 + 2(-4) -11 = 29 Find the x-intercepts. How would we show them in (x, y) form?
For f(x) = 3x 2 + 2x -11 Find x, if f(x) = 6. Hint: how do you set this up?
For f(x) = 3x 2 + 2x -11 Find x, if f(x) = 6. Set the y side equal to 0, and use the quadratic formula. Because the discriminant is a non- negative number, we will have real roots.
For f(x) = 3x 2 + 2x -11 Will f(x) ever equal -5? Will it ever equal -15?
For f(x) = 3x 2 + 2x -11 Will f(x) ever equal -5? Again, we can tell this is possible because of the discriminant.
For f(x) = 3x 2 + 2x -11 Will it ever equal -15? In this case, a negative discriminant tells us that this is not possible– the graph does not reach down to -15.
For f(x) = 3x 2 + 2x -11 Graph the parabola on your calculators. Does the parabola ever cross the line y = -5 or the line y = -15?
For f(x) = 3x 2 + 2x -11 Graph the parabola on your calculators. Does the parabola ever cross the line y = -5 or the line y = -15?