(2a+b)(2a-b)

To simplify the expression \((2a + b)(2a - b)\), you can use the difference of squares formula, which states that \( (x + y)(x - y) = x^2 - y^2 \).

Here, let \( x = 2a \) and \( y = b \). Thus, we can rewrite the expression as:

\[ (2a + b)(2a - b) = (2a)^2 - (b)^2 \]

Now, calculate \( (2a)^2 \) and \( (b)^2 \):

\[ (2a)^2 = 4a^2 \] \[ (b)^2 = b^2 \]

Putting it all together, we have:

\[ (2a + b)(2a - b) = 4a^2 - b^2 \]

So, the simplified expression is:

\[ 4a^2 - b^2 \]