Question

Desmond builds a set of towers out of blocks. The table shows the number of blocks in each tower. Tower # 1 2 2 3 4 5 Number of blocks 5 10 20 40 80 Which explicit formula correctly represents the number of blocks, an, in terms of the tower number, n? A. an = n + 80 B. an = 2n + 5 C. An = 5(2)n-1 D. an = 10(5)​

Answer 1

C

Explanation:

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Answer 2

C. An = 5(2)^n-1

Explanation:

Tower 1 2 3 4 5

Number of blocks 5 10 20 40 80

Where,

n = tower number

An = number of blocks

A. an = n + 80

B. an = 2n + 5

C. An = 5(2)^n-1

D. an = 10(5)^n

Checking all options

A. An = n + 80

When n = 1

An = 1 + 80

= 81

B. An = 2n + 5

When n = 1

= 2(1) + 5

= 2 + 5

= 7

C. An = 5(2)^n-1

When n = 1

= 5(2)^1-1

= 5(2)^0

2^0 = 1

= 5(1)

= 5

D. An = 10(5)^n

When n = 1

= 10(5)^1

5^1 = 5

= 10(5)

= 50

The explicit formula which correctly represents the number of blocks, an, in terms of the tower number, n is C. An = 5(2)^n-1