Integral of x cos^2x

For example, for n = 4, ( x + y ) 4 = x 4 + 4 x 3 y + 6 x 2 y 2 + 4 x y 3 + y 4 . {\displaystyle (x+y)^{4}=x^{4}+4x^{3}y+6x^{2}y^{2}+4xy^{3}+y^{4}.} The coefficient a in the term of axbyc is known as the binomial coefficient ( n b ) {\displaystyle {\tbinom {n}{b}}} or ( n c ) {\displaystyle {\tbinom {n}{c}}} (the two have the same value). ................
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