Pls help its not for me but could you still help my brother?

At which value in the domain does f(x) =0?

Find the vertex of the function given below y=x^2-6x+1

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