Answer:
Step-by-step explanation:
N is 3 bc #of terms minus 1
Exponents go from 3>2>x>none
Can be factored using binomial theorem
20 ÷ 2 (5,5)
20 ÷ 2 (25)
20 ÷ 50
.4
Answer:
C. $11.20.
Step-by-step explanation: Just times the minutes by the $0.77 cents then plus the $5.81 to the answer getting your final answer.
9514 1404 393
Answer:
sum = ∑[n=1,5] 4^(n-4)
Step-by-step explanation:
First of all, you need to be able to describe the n-th term.
Here, we have ...
term #: 1, 2, 3, 4, 5
value: 4^-3, 4^-2, 4^-1, 4^0, 4^1
That is, the exponent of 4 is 4 less than the term number. So, the n-th term is 4^(n-4). The sum of the 5 terms shown is then ...

A + b = 15 ..... eq 1
a – b = 12 ...... eq 2
So a = 15 – b
Substitute in eq 2 :
15 – b – b = 12
15 – 2b = 12
–2b = 12 – 15
b = 1.5
So a = 15 – 3/2 = 13.5
4ab = 4 x 13.5 x 1.5 = 81