Just in case you don't get the "binomials equal to 0 part"  this fact that you can use the two factors to solve for x comes from the "zero property of multiplication". If two numbers (known as factors) give a product of zero when multiplied together, then the only way...

You are right, you need a piecewise function, which you can separate based on the the segments of the domain that are given in words... First, there is the the segment from 0-400 kwh, then the segment from 400 - infinity (what an electric bill!)   Here is how to write...

The slopes of two perpendicular lines, when multiplied, have a product of -1.  Therefore, given the eq of the line with a slope of -1/3, we can conclude that the perpendicular line will have a slope of 3. so to start, our equation of interest is y=3x + b, where b is unknown.  Since...

I think you should play angry birds! No really, we do it in math class all the time.  A quadratic equation describes a parabola, which just happens to be the shape of the curve made by the bird as it is sling-shotted through the air.  Well, really it is an inverted parabola, and I will...

If your friend likes art, you can use that to motivate discussions about math.  For instance symmetry is a concept that has a lot of art application, as do triangles, squares, etc.  It all depends on what subject she is studying.  You can find interesting lesson plans and tools on...