Prove Hint: Consider (1 ? 1)n and (1 + 1)n, or use

Chapter 1, Problem 12E

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QUESTION:

Prove

           \(\sum_{r=0}^{n}(-1)^{r}(n r)=0\) and \(\sum_{r=0}^{n}(n r)=2^{n}\)

HINT: Consider \((1-1)^{n}\) and \((1+1)^{n}\), or use Pascal's equation and proof by induction.

Equation Transcription:

 

 

Text Transcription:

Sum _r=0^n(-1^)r(nr)=0

Sum _r=0^n(nr)=2^n

 (1-1)n

(1+1)n

Questions & Answers

QUESTION:

Prove

           \(\sum_{r=0}^{n}(-1)^{r}(n r)=0\) and \(\sum_{r=0}^{n}(n r)=2^{n}\)

HINT: Consider \((1-1)^{n}\) and \((1+1)^{n}\), or use Pascal's equation and proof by induction.

Equation Transcription:

 

 

Text Transcription:

Sum _r=0^n(-1^)r(nr)=0

Sum _r=0^n(nr)=2^n

 (1-1)n

(1+1)n

ANSWER:

Solution 12E

Step1 of 3:

We need to prove,

nCr =0  and  =

Consider (1 − 1)n and (1 + 1)n, or use Pascal’s equation and proof by induction.

Step2 of 3:

Consider,

nCr = 0

Proof: we know that the pascal’s equation is given by

nCr

Substitute a = -1 and b = 1 in above equation we get

nCr

         = nCr

             0 = nCr

             0 = n

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