= 4x*(y+2) / (y-2)(y+2)*2x^4 = 2 / (y-2)*x = 2 / xy-2x
= (2m-n)*3n / (2m-n)(2m-n) = 3n / 2m+n
= (m-1)(m+1) / 2(m+1) = m-1 / 2
= a(a-3) / a-3 = a
= (a-b)(a²+ab+b²) / a(a-b) = (a²+ab+b²)/a
=(m-n)(m+n) / (m-n)(m²+mn+n²) = (m+n) / (m²+mn+n²)
= (a+1)(a²-a+1)(a-1) / (a²-a+1) = (a+1)(a-1) = a²-1
= (b-1)(b+1)(b²+b+1) / (b-1)(b²+b+1) = b+1