To interpret the shapes you've described:
- Unshaded squares (x): Represent positive \( x \), and you have 2 of them, which equals \( 2x \).
- Shaded squares (-x): Represent negative \( x \) (or -1 for each x), and you have 1 shaded square, which equals \(-x\).
- Unshaded circles (1): Represent positive 1, and you have 2 of them, which equals \( 2 \).
- Shaded circles (-1): Represent negative 1 (or -1 for each circle), and you have 2 shaded circles, which equals \(-2\).
Now let's combine these:
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Combine the contributions from the squares: \[ 2x - x = x \]
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Combine the contributions from the circles: \[ 2 - 2 = 0 \]
Putting it all together, the algebraic expression represented by your model is: \[ x + 0 = x \]
So, none of the responses provided (3x + 4, 3x, x + 4) exactly matches \( x \). Assuming there is an oversight, if \( x \) was meant to be included in terms of options, the equivalent expression would simply be: \[ x \] However, since this isn't one of the listed responses, it seems like there may be a misunderstanding or error regarding the options provided.