The second difference 4;x;8;y;20; is 2​

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Step-by-step explanation:

First differences are ...

  x -4, 8 -x, y -8, 20 -y

Then second differences are ...

  (8 -x) -(x -4)

  (y -8) -(8 -x)

  (20 -y) -(y -8)

Each of these is said to be 2, so we have ...

  12 -2x = 2   ⇒   x = 5

  28 -2y = 2   ⇒   y = 13

And an equation we can use to check:

  x +y -16 = 2   ⇒   5 +13 -16 = 2 . . . . true

The explicit formula for the sequence is ...

  an = n^2 -2n +5

fahrenheit

step-by-step explanation:

fahrenheit is more precise than celsius. the ambient temperature on most of the inhabited world ranges from -20 degrees fahrenheit to 110 degrees fahrenheit—a 130-degree range. on the celsius scale, that range is from -28.8 degrees to 43.3 degrees—a 72.1-degree range. this means that you can get a more exact measurement of the air temperature using fahrenheit because it uses almost twice the scale.

step-by-step explanation:

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