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1.Algebra Booster

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6.46 Algebra <strong>Booster</strong><br />

A1<br />

Ê 1 1 1 1 ˆ<br />

= 1<br />

A Á + + + + +<br />

0 Ë 2 3 4 n + 1˜<br />

¯<br />

Ê 1 1 1 1 ˆ<br />

A1= A0Á1<br />

+ + + + +<br />

Ë 2 3 4 n + 1˜<br />

¯<br />

Ê 1 1 1 1 ˆ<br />

A1<br />

= n! ¥ Á1+ + + + +<br />

Ë 2 3 4 n + 1˜<br />

¯<br />

40. Clearly,<br />

A r<br />

= C r<br />

fi<br />

n A r<br />

= n C r<br />

Also,<br />

B r<br />

= C r<br />

fi<br />

n+1 B r<br />

= n+1 C r<br />

Now, A r<br />

+ A r–1<br />

= n A r<br />

+ n A r+1<br />

= n C r<br />

+ n C r+1<br />

= n+1 C r<br />

= n+1 B r<br />

= B r<br />

Hence, the result.<br />

Ê 1 1 ˆ<br />

41. Let S = Â Â +<br />

Á n n<br />

0£< £ C C ˜<br />

Ë ¯<br />

fi<br />

fi<br />

fi<br />

fi<br />

na<br />

fi S =<br />

2<br />

42. We have,<br />

i j n i j<br />

Ê Ê n -i n- j ˆˆ<br />

=<br />

Á Â Â +<br />

Á n n<br />

0£< i j£ n Cn-i<br />

C ˜˜<br />

Ë Ë<br />

n-<br />

j¯¯<br />

È Ê 1 1 ˆ<br />

= Ín<br />

  +<br />

Á n n<br />

0 i j n Ci C ˜<br />

ÍÎ<br />

£< £ Ë<br />

j¯<br />

Ê i j ˆ˘<br />

- Â Â +<br />

Á n n<br />

0£< i j£ n Cn-i C ˜˙<br />

Ë<br />

n-<br />

j¯˙˚<br />

Ê 1 1 ˆ<br />

= n   + - S<br />

Á ˜<br />

¯<br />

n n<br />

0£< i j£<br />

n Ë Ci Cj<br />

Ê 1 1 ˆ<br />

2S<br />

= n   +<br />

Á ˜<br />

¯<br />

n n<br />

0£< i j£<br />

n Ë Ci Cj<br />

Ê<br />

n<br />

n<br />

Ên - rˆ Ê r ˆˆ<br />

2S<br />

= nÁÂÁ ˜<br />

+ ÂÁ n ˜<br />

Ë ¯ Ë C ˜<br />

Ë<br />

¯¯<br />

n<br />

r= 0 Cr<br />

r=<br />

0<br />

Ê n Ê n ˆˆ<br />

2S<br />

= nÁÂ<br />

Á n ˜˜<br />

Ër<br />

= 0Ë<br />

Cr<br />

¯¯<br />

2Ê<br />

n<br />

Ê 1 ˆˆ<br />

2<br />

2S = n ÁÂ<br />

Á<br />

n a<br />

n ˜ =<br />

r = 0Ë<br />

C ˜<br />

Ë ¯¯<br />

n<br />

n<br />

ÂÂ<br />

2<br />

i= 0 j=<br />

0<br />

( C + C )<br />

i<br />

j<br />

r<br />

r<br />

n n<br />

n n<br />

ÂÂ Ci<br />

ÂÂ Cj<br />

i= 0 j= 0 i= 0 j=<br />

0<br />

n n n n<br />

ÂÂ Ci<br />

ÂÂ<br />

j= 0 i= 0 i= 0 j=<br />

0<br />

n<br />

n<br />

n<br />

n<br />

= ( ) + ( )<br />

Ê ˆ Ê ˆ<br />

= Á ( ) ˜ + Á ( Cj)<br />

˜<br />

Ë ¯ Ë ¯<br />

Â<br />

Â<br />

= (2 ) + (2 )<br />

j= 0 i=<br />

0<br />

n<br />

n<br />

n<br />

n<br />

Â<br />

Â<br />

= 2 (1) + 2 (1)<br />

j= 0 i=<br />

0<br />

= 2 n (n + 1) + 2 n (n + 1)<br />

= (n + 1)2 n–1<br />

43. We know that<br />

fi<br />

fi<br />

fi<br />

fi<br />

n n n<br />

ÂÂ<br />

Â<br />

( C + C ) = ( C + C )<br />

i j i j<br />

i= 0 j= 0 i=<br />

0<br />

n<br />

n + 1 n n<br />

 Â<br />

+ 2 ( C + C )<br />

0£< i j£<br />

n<br />

( n + 1)2 = 2 + 2 + 2 ( C + C )<br />

n + 1<br />

n<br />

n<br />

i<br />

 Â<br />

0£< i j£<br />

n<br />

n<br />

 Â<br />

( n + 1)2 = 2.2 + 2 ( C + C )`<br />

n<br />

n<br />

0£< i j£<br />

n<br />

0£< i j£<br />

n<br />

( n + 1)2 = 2 + ( C + C )<br />

n<br />

 Â<br />

0£< i j£<br />

n<br />

44. We have,<br />

n n<br />

ÂÂ ( CC i j)<br />

=<br />

i= 0 j=<br />

0<br />

45. We know that<br />

fi<br />

fi<br />

fi<br />

fi<br />

46. We have,<br />

n<br />

 Â<br />

( C + C ) = n◊2<br />

i<br />

j<br />

n<br />

Â<br />

n<br />

Â<br />

n<br />

( C ) ( C )<br />

i<br />

i= 0 j=<br />

0<br />

= (2 n ) ¥ (2 n )<br />

= (2 2n )<br />

Ê<br />

ÂÂ n n n n<br />

2<br />

( CC i j) = Á Â Ci ˜ + 2 Â Â ( CC i j)<br />

i= 0 j= 0 Ëi= 0 ¯ 0£ i< j£<br />

n<br />

Â<br />

n n n n<br />

2<br />

C Â Ê ˆ<br />

i Cj = Á Â Ci ˜ + Â Â CC i j<br />

i= 0 j= 0 Ëi= 0 ¯ 0£ i< j£<br />

n<br />

n<br />

n n 2n<br />

2 ◊ 2 = Cn + 2 ◊ Â Â( CC i j)<br />

0£< i j£<br />

n<br />

n<br />

2n<br />

2n<br />

2 = Cn + 2 ◊ Â Â( CC i j)<br />

0£< i j£<br />

n<br />

n<br />

1 2n<br />

2n<br />

 Â( CC i j) = (2 - Cn)<br />

0£< i j£<br />

n<br />

2<br />

ˆ<br />

( ) ( ) 2 ( )<br />

n<br />

 Â<br />

0£< i j£<br />

n<br />

(( i ¥ j) CC )<br />

i<br />

j<br />

i<br />

j<br />

i<br />

j<br />

j<br />

i<br />

j<br />

j

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