(-0,8x-0,5b)²

To simplify the expression \((-0.8x - 0.5b)^2\), you can use the formula for squaring a binomial, which is given by \((a + b)^2 = a^2 + 2ab + b^2\).

In your case, we can identify \(a = -0.8x\) and \(b = -0.5b\). Let's apply the formula step by step:

1. Square the first term: \[ (-0.8x)^2 = 0.64x^2 \]

2. Square the second term: \[ (-0.5b)^2 = 0.25b^2 \]

3. Multiply the two terms together and then double it: \[ 2 \cdot (-0.8x) \cdot (-0.5b) = 0.8x \cdot 0.5b = 0.4xb \quad \text{(and including the factor of 2)} \quad = 0.8xb \]

Now, putting it all together, we have:

\[ (-0.8x - 0.5b)^2 = 0.64x^2 + 0.8xb + 0.25b^2 \]

So, the simplified form of \((-0.8x - 0.5b)^2\) is:

\[ \boxed{0.64x^2 + 0.8xb + 0.25b^2} \]