A Heart Equation Lesson for Alg1 through PreCalc - Happy Valentine's!

This is a great lesson on or just before Valentine's Day that emphasizes a function-based approach to algebra and targets the following two Common Core Mathematical Practices:

• Look for and make use of structure.
• Use appropriate tools strategically.

It is written for the TI-Nspire, but it works just as nicely on an TI-73, 83 or 84 - or any graphing app!

Graph V(x) = abs(x) +/- sqrt(1-x^2);

BUT first predict the results by thinking about adding the following two functions:

f1(x) = abs(x) + f2(x) = sqrt(1-x^2)

and

f3(x) = abs(x) + f4(x) = - sqrt(1-x^2)

The attached lesson details an approach to guide this thinking.