A geometric sequence is defined by the explicit formula an = 5(-4)n-1. What is the recursive formula for the nth term of this sequence?

A. an = -5an-1
B. an+1 = 4an
C. an+1 = 5an
D. an = -4an-1
someone please help me...

Question

A geometric sequence is defined by the explicit formula an = 5(-4)n-1. What is the recursive formula for the nth term of this sequence?

 		A.	an = -5an-1
 		B.	an+1 = 4an
 		C.	an+1 = 5an
 		D.	an = -4an-1
someone please help me...

solomonzelman · Answer

$\large\color{slate}{   a_n = 5(-4)^n-1   }$      like this ?

anonymous · Answer

yes

anonymous · Answer

except its n-1

solomonzelman · Answer

oh,   $\large\color{slate}{   a_n = 5(-4)^{n-1}   }$    this ?

anonymous · Answer

yes!!

solomonzelman · Answer

$\large\color{slate}{   a_n = 5(-4)^{n-1}   }$

$\large\color{slate}{   a_n = 5(-4)^{n} (-4)^{-1}  }$

$\large\color{slate}{ \displaystyle  a_n = 5(-4)^{n} \frac{1}{4}  }$

$\large\color{slate}{ \displaystyle  a_n = \frac{5}{4} (-4)^{n}  }$

solomonzelman · Answer

that is not any of the options though, is it....

solomonzelman · Answer

your options are very difficult to read, perhaps you can screenshot them or draw?

solomonzelman · Answer

I made a mistake in my conslusion

solomonzelman · Answer

$\large\color{slate}{ \displaystyle  a_n = -\frac{5}{4} (-4)^{n}  }$
because it is negative 1/4 and on...... but will try to get it to one of your options

anonymous · Answer

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