50a3 + 10a2
A10a2(5a + 1)
B5a2(10a + 2)
C10a2(5a - 1)
D10a(5a2 + 1a)
A10a2(5a + 1)
B5a2(10a + 2)
C10a2(5a - 1)
D10a(5a2 + 1a)