bino

(1+x)10 = a0 + a1 x +a2 x2 + ..... + a10 x10

then,

(a0 - a2 + a4 - a6 + a8 - a10)2 + (a1 - a3 + a5 - a7 + a9)2

is equal to : ??

11 Answers

21
tapanmast Vora ·

0 KYA????

21
tapanmast Vora ·

1st term will be zero.....

2nd term socjna padega

1
skygirl ·

no not zero re :(

21
tapanmast Vora ·

1st term zero.........

1357
Manish Shankar ·

try it putting x=i
and taking modulus

1
skygirl ·

oh bhaiyaaaaa u are great!!!

yes got it!!

took one x=i and another x=-i and multiplied ....

wow!!!!!!!!!

1
skygirl ·

tell me on thing... how did this 'i' thing came to your mind ???

wow !

its simply sweet !!!

1357
Manish Shankar ·

putting x=i you will get

(1+i)10=(a0-a2+a4-a6+a8-a10)+i(a1-a3+a5-a7+a9)

takiking modulus

(a0-a2+a4-a6+a8-a10)2+(a1-a3+a5-a7+a9)2=(|1+i|2)10=210

why take separate cases if it can be solved in one

1357
Manish Shankar ·

hehe

first I was trying to put 1 or -1, then iota came in my mind

1
skygirl ·

no actually i din see your post .. i thnk u edited later...

firstly wen u wrote take x=i .. i took it .. and then
since i am a bit stupid ... that mod thing din came to mind
and i took x=-i and multiplied ....

but great bhaiya!

11
Subash ·

As a backdrop to this one i recommend everyone to look into this one

http://targetiit.com/iit_jee_forum/posts/great_one_2452.html

similar logic

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