Respuesta :

Given

[tex]\Sigma_{n=1}^\infty15(-4)^n[/tex]

The first 10 partial sums are as follows:

[tex]S_1=\Sigma_{n=1}^{1}15(-4)^n=15(-4)=\bold{-60} \\ \\ S_2=\Sigma_{n=1}^{2}15(-4)^n=\Sigma_{n=1}^{1}15(-4)^n+15(-4)^2 \\ =-60+15(16)=-60+240=\bold{180} \\ \\ S_3=\Sigma_{n=1}^{3}15(-4)^n=\Sigma_{n=1}^{2}15(-4)^n+15(-4)^3 \\ =180+15(-64)=180-960=\bold{-780} \\ \\ S_4=\Sigma_{n=1}^{4}15(-4)^n=\Sigma_{n=1}^{3}15(-4)^n+15(-4)^4 \\ =-780+15(256)=-780+3,840=\bold{3,060} \\ \\ S_5=\Sigma_{n=1}^{5}15(-4)^n=\Sigma_{n=1}^{4}15(-4)^n+15(-4)^5 \\ =3,060+15(-1,024)=3,060-15,360=\bold{-12,300}[/tex]

[tex]S_6=\Sigma_{n=1}^{6}15(-4)^n=\Sigma_{n=1}^{5}15(-4)^n+15(-4)^6 \\ =-12,300+15(4,096)=-12,300+61,440=\bold{49,140}[/tex]

The rest of the partial sums can be obtained in similar way.

Find 10 partial sums of the series. (Round your answers to five decimal places.)

15 /(−4)n

 Do calculations based on answer above (i.e. 15/(-4)^1 + 15/(-4)^2+...

1  

-3.75000

 

Correct: Your answer is correct.

2  

-2.81250

 

Correct: Your answer is correct.

3  

-3.04688

 

Correct: Your answer is correct.

4  

-2.98828

 

Correct: Your answer is correct.

5  

-3.00293

 

Correct: Your answer is correct.

6  

-2.99927

 

Correct: Your answer is correct.

7  

-3.00018

 

Correct: Your answer is correct.

8  

-2.99995

 

Correct: Your answer is correct.

9  

-3.00001

 

Correct: Your answer is correct.

10  

-3.00000

 

Correct: Your answer is correct.

Graph both the sequence of terms and the sequence of partial sums on the same screen.

WebAssign Plot WebAssign Plot

WebAssign Plot WebAssign Plot

Correct: Your answer is correct.  (The one converging near -3, black dots)

Is the series convergent or divergent?

convergent

Correct: Your answer is correct.

If it is convergent, find the sum. (If the quantity diverges, enter DIVERGES.)

set up calculations to determine convergence (geometric)

a/1-r

a=15/-4 , r=1/-4

 

-3

Correct: Your answer is correct.