Question

7x2-9x2

Answer 1

-2x^2

Answer 2

7x^(2)-9x^(2)

Since 7x^(2) and -9x^(2) are like terms, add -9x^(2) to 7x^(2) to get -2x^(2).
-2x^(2)

Answer 3

thanks so much
here is another one