To add the polynomial expressions \(2r^2 - 3r + 4\) and \(-2r^2 + 3r + 6\), we combine like terms.
Starting with the two polynomials:
\[ (2r^2 - 3r + 4) + (-2r^2 + 3r + 6) \]
Now we can group the like terms:
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For the \(r^2\) terms: \[ 2r^2 + (-2r^2) = 0 \]
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For the \(r\) terms: \[ -3r + 3r = 0 \]
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For the constant terms: \[ 4 + 6 = 10 \]
Now, combining all these results:
\[ 0 + 0 + 10 = 10 \]
Thus, the sum of the polynomial expressions \(2r^2 - 3r + 4\) and \(-2r^2 + 3r + 6\) is:
\[ \boxed{10} \]