Answer:
[tex]12a^2-9a+5[/tex]
Step-by-step explanation:
We need to subtract
[tex]-7a^2+3a-9[/tex]
from
[tex]5a^2-6a-4[/tex]
So
[tex]5a^2-6a-4-(-7a^2+3a-9)[/tex]
Opeining the bracket changes the signs
[tex]=5a^2-6a-4+7a^2-3a+9[/tex]
Bringing all the like terms together
[tex]=5a^2+7a^2-6a-3a-4+9[/tex]
[tex]=12a^2-9a+5[/tex]
The result after performing the required operation is [tex]12a^2-9a+5[/tex].