1,345,456,234,234,345,234,-1234,567 ,890=? My subsititue is being mean so we can not use calculatars and I do not like to cheat anyway but in this case (yes)

Can someone explain the elimination method to me for this problem?

Proceed as in example 3 in section 6.1 to rewrite the given expression using a single power series whose general term involves xk. ∞ n(n − 1)cnxn − 2 n = 2 − 4 ∞ ncnxn n = 1 + ∞ cnxn n = 0

Me with geometry ! in this figure, bc is a perpendicular bisects of kj. dm is the angle bisects of bdj. what is the measure of bdm? •60° •90° •30° •45°