Answer:
correct
incorrect
incorrect
Step-by-step explanation:
[tex]\begin{aligned}(5a-8)+(2a^2+2a-1)&=5a-8+2a^2+2a-1\\& = 2a^2+5a+2a-8-1\\ & = 2a^2+7a-9\end{aligned}[/tex]
[tex]\implies (5a-8)+(2a^2+2a-1)=2a^2+7a-9\quad\textsf{is correct}[/tex]
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[tex]\begin{aligned}(b^2+6b-4)-(3b+b^2) &=b^2+6b-4-3b-b^2\\ & = b^2-b^2+6b-3b-4\\& = 3b-4\end{aligned}[/tex]
[tex]\implies (b^2+6b-4)-(3b+b^2)=2b^2+3b-4\quad\textsf{is incorrect}[/tex]
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[tex]\begin{aligned}(9c-4c^2)-(2c^2+c) &=9c-4c^2-2c^2-c\\ & = -4c^2-2c^2+9c-c\\& = -6c^2+8c\end{aligned}[/tex]
[tex]\implies (9c-4c^2)-(2c^2+c)=-6c^2+10c\quad\textsf{is incorrect}[/tex]
