Exercise 4.3 (PCTB)

1. Find HCF by factorization method (i) \( 21x^2y, 35xy^2 \) \[21x^2y = 3 \cdot 7 \cdot x^2 \cdot y, \quad 35xy^2 = 5 \cdot 7 \cdot x \cdot y^2\] \[\text{HCF} = 7xy\] (ii) \( 4x^2 – 9y^2, 2x^2 – 3xy \) \[4x^2 – 9y^2 = (2x + 3y)(2x – 3y), \quad 2x^2 – 3xy…