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What is the coeffiicient of x^2 y^2 in the expansion of (x + y)^4 + (x + 3y)^4?

 Nov 24, 2020
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C(4,2) ( x)^2 (y)^2     =   6x^2y^2

 

C(4,2)   ( x)^2  ( 3y)^2  =  6x^2 * 9y^2  =  54x^2y^2

 

(6 + 54) x^2 y ^2  = 

 

60 x^2y^2

 

cool cool cool

 Nov 24, 2020

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