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1. In the expansion of (ax2 - 9) 5 in descending powers of x, the coefficients of the 2nd term and the 3"d term are -810 and 1080, respectively. What is the coefficient of the 4" term?2. Let Pt) be the statement (1;2)(1;1)[1j2)...(1$)=\";1. By mathematical induction, prove that Flirt) is true for all positive integers n E 2