The quadratic formula is 
.
From the problem, a is 1, b is -1, and c is 12. Plugging in these values gives:
Because there is a square root of a negative number, there is no solution.
Missing questions and subsequent solutions:
(a) Write an equation for company A for cost, C, number of months, n, that Beni will pay for the phone.
Solution:
For company A:
C = 72.25 + 85.50n
(b) Write an eqyation for company B for cost, C, and number of months, n, that Bei will pay for the phone.
Solution:
For company B:
C = 151.25 + 65.75n
(c) Write an inequality when the cost from company A is better than cost from company B.
Solution:
72.25 + 85.50n ≤ 151.25 + 65.75n
(85.50-65.75)n ≤ (151.25 - 72.25)
19.75 n ≤ 79
n ≤ 4
(d) Value of n for which cost from the two companies will be the same.
Solution:
If cost for companies A and B are the same, then
72.25 + 85.50n = 151.25 + 65.75n
(85.5 - 65.75)n = 151.25 - 72.25
19.75n = 79
n = 79/19.75 = 4 months
After 4 months,
C = 72.25 + 85.5*4 = $414.25
Compound interest:
where
is the amount you start with,
is the interest rate,
is the number of times interest is compounded per year, and
is amount of time that passes.
For 1. To estimate how many sports cards Alberto had, you would round each number to the nearest ten, so 318 would become 320. 273 would then become 270. You would then add those two and would get 590. So, Alberto had 590 sports cards (estimated). If you were looking for the actual answer (not estimated) , you would get 591.
