Respuesta :

nileinperera57

Answer:

a1 = 5

Step-by-step explanation:

1. Substitute S16 = -160 into the second formula.

2. solve as mush as possible

3. a16 is given. substitute.

4. solve

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semsee45

Answer:

[tex]a_1=5[/tex]

Step-by-step explanation:

Given:

  • [tex]S_{16}=-160[/tex]
  • [tex]a_{16}=-25[/tex]

[tex]\textsf{Use}\quad S_n=\dfrac{n}{2}(a_1+a_n):[/tex]

[tex]\begin{aligned}S_{16} &=-160\\\implies S_{16}=\dfrac{16}{2}(a_1+a_{16}) &=-160\\\implies \dfrac{16}{2}(a_1+(-25)) & =-160\\8(a_1-25) &=-160\\a_1-25 &=-20\\a_1&=-20+25\\a_1 &=5\end{aligned}[/tex]

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