Вправи: 159

159. Перетворіть на дріб:

1) (4a + 20b) • 5a2-25b2 = 4a+5b • 5(a-5b)(a+5b) = 20a-5b;

2) (m² – 4) • m(m-2)2 = (m-2)(m+2)m(m-2)2 = m(m+2)m-2;

3) –a2a2-18 • (a² – 6a + 9) = –a(a-3)22(a2 -9) = –a(a-3)22(a-3)(a+3) = –a(a-3)2(a+3) = a(3- a)2(a+3);

4) (x³ + 27y³) • 13x2-9xy+27y2 = (x+3y)(x2 -3xy+9y2)3(x2 -3xy+9y2) = x+3y3.