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I need help like now i only have 15 sec make it as quick as possible.

I need help like now i only have 15 sec make it as quick as possible.-example-1
User Idungotnosn
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1 Answer

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21 votes

In general, an arithmetic sequence is given by the following formula


a_n=a_1+(n-1)d

Where d is a constant.

In our case, notice that (1,-8)=(1,a_1), and (2,-2)=(2,a_2); thus,


\begin{gathered} a_1=-8_{} \\ \text{and} \\ a_2=a_1+(2-1)d=a_1+d \\ \Rightarrow a_2=-8+d \\ \text{but} \\ a_2=-2 \\ \Rightarrow-2=-8+d \\ \Rightarrow d=-2+8=6 \\ \Rightarrow d=6 \end{gathered}

Thus, the explicit formula is


\begin{gathered} \Rightarrow a_n=-8+6(n-1) \\ \text{with} \\ d=6 \end{gathered}

The answers are d=6, a_n=-8+6(n-1)

User CampSafari
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