Answer:
1. 6a+8b
2. [tex]4^3+8^2x[/tex][tex]-9[/tex]
3. 12mn-m
Step-by-step explanation:
1. (5a+7b)+(-3a+2b)+(4a-b)
Eliminate redundant parentheses
5+7−3+2b+4a−
Combine like terms
6+7+2−
Combine more terms
6a+8b
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2. (-2x^3+4x^2+x)+(6x^3+4x^2-9)
Eliminate redundant parentheses
−2^3+4^2++6^3+4^2−9
Combine like terms
4^3+4^2+x4^2−9
Combine more terms
4^3+8^2+−9
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3. (10mn-5m+3n)+(mn-5m-3n)+(mn+9m)
