After you rewrite subtraction as addition of the
additive inverse, how can the like terms be
grouped?
[3a2 + (-3a2)] + (-5ab + 8ab) + [b2 + (-2b2)]
[3a2 + (-3a2)] + (-5ab + 8ab) + (b2 + 262)
© (3a2 + 3a2) + (-5ab + (-8ab)] + [b2 + (-262)]
(3a2 + 3a2) + (-5ab + (-262)] + [b2 + (-8ab)]