As given,
(a2 – 5a)2 – 36
= (a2 – 5a)2 – 62
= (a2 – 5a)2 – 62 = (a2 – 5a + 6) (a2 – 5a – 6)
= a2 -5a – 6
= a2 + a – 6a – 6
= a (a + 1) -6(a + 1)
= (a – 6) (a + 1)
= a2 -5a + 6
= a2 – 2a – 3a + 6
= a (a – 2) -3 (a – 2)
= (a – 3) (a – 2)
∴ (a2 – 5a)2 – 36
= (a2 – 5a + 6) (a2 – 5a – 6)
= (a + 1) (a – 6) (a – 2) (a – 3)