Answer the following questions on the concept of the greatest common factor (GCF) of polynomials:
a. (i) Define the GCF of two or more polynomial terms and illustrate your definition with an example involving the terms 12x3 and 18x2.
b. (ii) Explain, in about two to three sentences, why removing the GCF is generally taken as the first step while factorising any polynomial.
c. (iii) For the polynomial 6x2−24x+18, determine its GCF and rewrite the polynomial after taking out this common factor.