Answer: -a^3+14a^2-a-6 Step-by-step explanation: [tex]a^{3}-7a^{2}+12a+13-x=7a^{2}+11a+7\\\\x= 7a^{2}+11a+7-(a^{3}-7a^{2}+12a+13)\\\\x=7a^{2} +11a+7-a^{3}+7a^{2}-12a-13\\\\x=-a^{3}+14a^{2}-a-6\\\\[/tex] I hope this helped pls mark as brainliest Reply
Answer:
-a^3+14a^2-a-6
Step-by-step explanation:
[tex]a^{3}-7a^{2}+12a+13-x=7a^{2}+11a+7\\\\x= 7a^{2}+11a+7-(a^{3}-7a^{2}+12a+13)\\\\x=7a^{2} +11a+7-a^{3}+7a^{2}-12a-13\\\\x=-a^{3}+14a^{2}-a-6\\\\[/tex]
I hope this helped
pls mark as brainliest