Answer:
5a^2+1
Explanation:
Combining like terms in polynomials can go based on the degree it has.
Since 7a^2 and -2a^2 have the same degree as one another, we can just add them, which gives us 5a^2
Now since -4 and 5 dont have any degree, they are liked terms.
Add: -4+5=1
Now when simplified, we get:
5a^2+1