U10. A1. Official Review

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An stadium has rows of seats in the form of a semi circle. There are 12 seats in row 1, 25 seats in row 2, and 38 seats in row 3. If the trend continues, what row will have exactly 129 seats?

The first five figures in a pattern are shown.

Each figure is made up of identical circles. If the pattern continues, which expression can be used to find the number of circles that make up Figure n?

• n ² + 2

• n ² + 2 n

• 2 n ² + 1

• 2 n ² + n

In a sequence, each number after the first number is obtained by adding 9 to the previous number. If the first number in the sequence is 12, which of the following expressions represents the nth number in the sequence?

• 12+9(n+1)

• 12+9(n-1)

• 12+9n

• 12+(9n-1)

If a sequence starts with 12 and increases by a factor of 5 before increasing by 3, what is the value of r?

If a sequence starts with 12 and increases by a factor of 5 before increasing by 3, what is the value of d?