## 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