3a2-9ab+4b2-7ab=

Answer 1

3a^2 = 3 (a squared) = 3 * a * a

However, (3a)^2 = 3a * 3a

Combine like terms.

3a^2 - 9ab + 4b^2 -7ab =

3a^2 - 16ab + 4b^2

I hope this helps. Thanks for asking.