Answer:
[tex]5x^2-4x-1[/tex]
Step-by-step explanation:
I am assuming you mean [tex](-2x^2-4x)-(-7x^2+1)[/tex]
If so, then the negative outside and inside the fraction flips the sign inside, therefore [tex]-(-7x^2+1)= 7x^2-1[/tex]
After that, we simply combine like terms.
[tex]-2x^2+7x^2=5x^2\\=5x^2-4x-1[/tex]
