XERCISE 8 (3) Factorise the following quadratic trinomials fully: (1) (2) (4) (5) a’ -9a+20 (7) a² - 12a+35 (8) (10) m² - 5m - 6 m (11) m² + 5m-6 (13) x2 + 7x+12 + (14) r? – 7x+12 Factorise fully (1) 2r2-21-12 (2) 3x? - 21x-54 (4) 6a2 +24a - 30 (5) x² + 2x² – 8x Explain why the trinomial x?+ 4x + 5 cannot factorise (6) (9) (12) (15) a? -11a-12 m² + 5m + 6 m2 - 5m + 6 + - - (3) (6) 4a? +12a-40 90 – 45x + 5x2 -