Factorise the following expressions: (i) 7x² (ii) 6p - 12q (iii) 7a² + 14a (iv) -8z + 20z² (v) 20l²m + 30alm (vi) 5x²y - xy² (vii) 10a² - b² + 20c² (viii) -a² + 4ab - ca (ix) x²yz + xy²z + xyz² (x) ax²y + bxy² + cxyz

To factorise the following expressions, first take common factors from both sides:
(i) 7x² = 7(x²)
(ii) 6p - 12q = 6(p - 2q)
(iii) 7a² + 14a = 7a(a + 2)
(iv) -8z + 20z² = 4z(-2 + 5z)
(v) 20l²m + 30alm = 10lm(2l + 3a)
(vi) 5x²y - xy² = xy(5x - y)
(vii) 10a² - b² + 20c² = This expression cannot be factorised further easily. It might need more context or a different approach.
(viii) -a² + 4ab - ca = -a(a - 4b + c)
(ix) x²yz + xy²z + xyz² = xyz(x + y + z)
(x) ax²y + bxy² + cxyz = xy(ax + by + cz)