CPM Homework Help : PCT Problem 1-25

Explain why $\left(3x + 2\right)^{2} ≠ 9x^{2} + 4$ ? Find the correct expansion.

Hint:

Complete the generic rectangle below and simplify. What is missing?

Generic rectangle, top & left edge, each labeled, 3, x + 2. Interior top left labeled, 9 x squared, bottom right labeled, 4.

The equation will be true if $x$ is a certain value. What is that value?