Which expression is equivalent to (7x^2-4)(5x+7)

Which of the following is the missing term, a2, of the geometric sequence in which a1=2 and a3=200

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle