If ΔABC ~ DEF such that AB = 1.2 mm and DE = 1.4 cm, the ratio of the areas of ΔABC and Δ DEF is

The common difference of an AP, whose n^th term is a_n = (3n + 7), is

The HCF of 135 and 225 is

The value of λ for which (x² + 4x + λ) is a perfect square, is

The value of k, for which the pair of linear equations kx + y = k² and x + ky = 1 have infinitely many solutions is