Алгебра 8 класс учебник Макарычев, Миндюк ответы – номер 121

а) x² − xy/y ⋅ y²/x = (x² − xy) ⋅ y²/y ⋅ x = x²y² − xy³/xy = xy(xy − y²)/xy = xy(xy − y²) : xy/xy : xy = xy − y²/1 = xy − y²
б) 3a/b² ⋅ ab + b²/9 = 3a ⋅ (ab + b²)/b² ⋅ 9 = 3ab(ab + b)/9b² = 3ab(ab + b) : 3b/9b² : 3b = a(ab + b)/3b
в) m − n/mn ⋅ 2mn/mn − m² = (m − n) ⋅ 2mn/mn ⋅ (mn − m²) = (m − n) ⋅ 2mn/mn ⋅ (−m(m − n)) = (m − n) ⋅ 2mn : (m − n)mn/mn ⋅ (−m(m − n)) : (m − n)mn = −2/m
г) 4ab/cx + dx ⋅ ax + bx/2ab = 4ab ⋅ x(a + b)/x(c + d) ⋅ 2ab = 4ab ⋅ x(a + b) : 2abx/x(c + d) ⋅ 2ab : 2abx = 2(a + b)/c + d
д) ma − mb/3n² ⋅ 2m/nb − na = −m(b − a) ⋅ 2m/3n² ⋅ n(b − a) = −m(b − a) ⋅ 2m : (b − a)/3n² ⋅ n(b − a) : (b − a) = −m ⋅ 2m/3n² ⋅ n = −2m²/3n³
е) ax − ay/5x²y² ⋅ (−5xy/by − bx = a(x − y) ⋅ 5xy/5x²y² ⋅ b(x − y) = a(x − y) ⋅ 5xy : (x − y)5xy/5x²y² ⋅ b(x − y) : (x − y)5xy = a/bxy