Use the process of completing the square and/or factoring to find the zeros and axis of symmetry for the graph of the function.

f(x) = x^2 - 14x - 72

a.

zeros: x = -4 and x = 18;

axis of symmetry: x = 7

b.

zeros: x = -18 and x = 4;

axis of symmetry: x = -7

c.

zeros: x = -9 and x = -8;

axis of symmetry: x = -7

d.

zeros: x = 9 and x = 8;

axis of symmetry: x = 7

edit: the answer is here.

the axis of symmetry is 7.
the roots were 18 & -4

Acell phone company offers two plans to its subscribers. at the time new subscribers sign up, they are asked to provide some demographic information. the mean yearly income for a sample of 40 subscribers to plan a is $45,000 with a standard deviation of $9,200. for a sample of 25 subscribers to plan b, the mean income is $64,300 with a standard deviation of $7,100. at the 0.025 significance level, is it reasonable to conclude the mean income of those selecting plan b is larger? assume unequal population standard deviations. hint: for the calculations, assume the plan a as the first sample. what is the decision rule? (negative amount should be indicated by a minus sign. round your answer to 3 decimal places.) compute the value of the test statistic. (negative amount should be indicated by a minus sign. round your answer to 2 decimal places.) what is your decision regarding h0 ? reject h0 fail to reject h0 compute the p-value. less than 0.01 between 0.01 and 0.025 between 0.025 and 0.05 between 0.05 and 0.10 greater than 0.10