Please helppp (had to have 20 words haha)

Factor completely. x^8 - 1/81 a) (x^4 + 1/9)(x^2 + 1/3)(x^2 - 1/3) b) (x^4 - 1/9)(x^2 + 1/3)(x^2 - 1/3) c) (x^4 + 1/9)(x^2 - 1/3)2

What is the range of this function? all real numbers such that y ≤ 40 all real numbers such that y ≥ 0 all real numbers such that 0 ≤ y ≤ 40 all real numbers such that 37.75 ≤ y ≤ 40

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