Four friends want to take a vacation together, so each one gets a part-time job. each person has 8 weeks to save $720 for the vacation. analyze the four individual plans below and decide which of the four people will reach his or her goal of saving $720 for vacation.
friend a: works 13 hours per week at $6.95 per hour.
friend b: works 15 hours per week at $5.85 per hour.
friend c: works 18 hours per week at $5.25 per hour.
friend d: works 11 hours per week at $7.80 per hour.
a.
a and c
b.
a and d
c.
b and c
d.
b and d

let's cover over the formula of the vertex:

y = a(x – h)^2 + k

in this formula, (h,k) are the vertex, always remember that the positive or negative value of the vertex is based on the sign it has.

for example, if the vertex is -3,-6 then both the x and y value would have the positive sign attached to it and if it were a positive x and y value, then a negative sign would be attached to it.

with that being said, for our problem the x value is a positive one so we are looking for a number with a negative sign next to it, in this case the first and second choice.

however, for the first answer choice it isn't quite part of the formula so we know that the answer choice correctly displays the x value.

to confirm, we can see if the -1 fits correctly with the second answer choice, and as mentioned above a negative number will have a positive sign attached to it. so, for our problem we can see that -1 has been changed to +1, so we can confirm that the second answer choice is correct.

hence, our final answer is y=(x - 1)^2 + 1