The Multiplication Parabola

In the graph below, move points A and B such that they are on opposite sides of the y-axis.  What do you observe?

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Theorem: Given two points on the function f(x) = x^2, whose coordinates are (a,a^2) and (b, b^2) with a < 0 and b > 0, the y-intercept of the line passing through these points is -ab. » Read more