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In an arithmetic sequence, term 10 is 33 and term 22 is -3. What are the first 4 terms

User Oneca
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1 Answer

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9514 1404 393

Answer:

60, 57, 54, 51, ...

Explanation:

The general term of an arithmetic sequence is ...

an = a1 +d(n -1)

We would like to find the first term (a1) and the common difference (d). We can use the two given terms to find these parameters.

a10 = 33 = a1 +d(10 -1)

a22 = -3 = a1 +d(22 -1)

Subtracting the first equation from the second, we get ...

(-3) -(33) = (a1 +21d) -(a1 +9d)

-36 = 12d

-3 = d

Using this value in the first equation, we can find a1.

33 = a1 +9(-3) = a1 -27

60 = a1 . . . . . . . . . . . . . . add 27 to both sides

So, our sequence has first term 60 and a common difference of -3.

The first 4 terms are ...

60, 57, 54, 51, ...

User Eugene Tsakh
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