Question 30051
(-6x^4 +3x^2 - 16) + (4x^2 + 4x - 7)
=-6x^4 +(3x^2+4x^2)+ 4x -16- 7  (grouping like terms which is ultimately applicaiton of repeated additive commutativity and associativity)
= -6x^4 + 7x^2+ 4x -23