1) write an expression to represent the pattern. 19, 27, 35,
2) write an expression to represent the sequence. 71, 62, 53,

1) The expression to represent the pattern is 11 + 8n

2) The expression to represent the pattern is 80 - 9n

Step-by-step explanation:

1) * Lets study the pattern;

- 19 , 27 , 35 , 43 ,

∵ 27 - 19 = 8

∵ 35 - 27 = 8

∵ 43 - 35 = 8

∴ The difference is constant between each two consecutive terms

∴ It is an arithmetic sequence

* Lets take about the arithmetic sequence

- If the first term is a and the constant difference is d

∴ a1 = a , a2 = a + d , a3 = a + 2d , a4 = a+ 3d ,

∴ an = a + (n - 1)d, where n the position of the term in the sequence

* Now we will use this rule to find the expression of our pattern

∵ a = 19 , d = 8

∴ an = 19 + (n - 1)(8) ⇒ an = 19 + 8n - 8 ⇒ an = 11 + 8n

* Lets check it;

∵ a3 = 11 + 8(3) = 11 + 24 = 35 ⇒ true

∴ The expression to represent the pattern is 11 + 8n

2) * Lets study the pattern;

- 71 , 62 , 53 , 44 ,

∵ 62 - 71 = -9

∵ 53 - 62 = -9

∵ 44 - 53 = -9

∴ The difference is constant between each two consecutive terms

∴ It is an arithmetic sequence

* We will use the same rule above to find the expression of the pattern

∵ a = 71 , d = -9

∴ an = 71 + (n - 1)(-9) ⇒ an = 71 + -9n + 9 ⇒ an = 80 - 9n

* Lets check it;

∵ a4 = 80 - 9(4) = 80 - 36 = 44 ⇒ true

∴ The expression to represent the pattern is 80 - 9n