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what is the 20th term if the first term is 4 and the common difference is -1/3?

 Jul 7, 2015

Best Answer 

 #2
avatar+26364 
+10

what is the 20th term if the first term is 4 and the common difference is -1/3

 

$$\small{
\text{d} = -\dfrac13 \qquad a_1 = 4
}\\\\
\small{
\text{arithmetical sequence: } a_n = a_1 + (n-1)\cdot d
}\\\\
\begin{array}{rclclcr}
\small{a_{20} &=& 4 + (20-1)\cdot \left( -\dfrac13 \right)\\\\
\small{a_{20} &=& 4 + 19\cdot \left(-\dfrac13 \right)\\\\
\small{a_{20} &=& 4 - \dfrac{19}{3} \\\\
\small{a_{20} &=& -2.\overline{3} \\\\
\end{array}$$

 

 Jul 7, 2015
 #1
avatar
0

its 4 for the startvalue + 20*-1/3 so => 4+20*(-1/3)= 2.666666

 Jul 7, 2015
 #2
avatar+26364 
+10
Best Answer

what is the 20th term if the first term is 4 and the common difference is -1/3

 

$$\small{
\text{d} = -\dfrac13 \qquad a_1 = 4
}\\\\
\small{
\text{arithmetical sequence: } a_n = a_1 + (n-1)\cdot d
}\\\\
\begin{array}{rclclcr}
\small{a_{20} &=& 4 + (20-1)\cdot \left( -\dfrac13 \right)\\\\
\small{a_{20} &=& 4 + 19\cdot \left(-\dfrac13 \right)\\\\
\small{a_{20} &=& 4 - \dfrac{19}{3} \\\\
\small{a_{20} &=& -2.\overline{3} \\\\
\end{array}$$

 

heureka Jul 7, 2015

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