Calculation of Y · y ^ n 1 - 2Y ^ n * y ^ 2 y ^ n-1y ^ 3 Can you explain every step of simplification? I don't know why it's 2Y ^ n * y ^ 2 y·y^n 1 -2y^n*y^2 y^n-1y^3

Calculation of Y · y ^ n 1 - 2Y ^ n * y ^ 2 y ^ n-1y ^ 3 Can you explain every step of simplification? I don't know why it's 2Y ^ n * y ^ 2 y·y^n 1 -2y^n*y^2 y^n-1y^3

y·y^n +1 -2y^n*y^2 +y^n-1y^3
=y^(1+n+1)-2·y^(n+2)+y^(n-1+3)
=y^(n+2)-2y^(n+2)+y^(n+2)
=2y^(n+2)-2y^(n+2)
=0
Main use
A power of X · B power of x = a + B power of X