i. p2 – q2
Here, a = p, b = q
∴ p2 – q2 = (p + q)(p – q)
….[(a2 – b2) = (a + b)(a – b)]
ii. 4x2 – 25y2
= (2x)2 – (5y)2
Here, a = 2x, b = 5y
∴ (2x)2 – (5y)2 = (2x + 5y)(2x – 5y)
….[(a2 – b2) = (a + b)(a – b)]
iii. y2 – 4
= y2 – 22
Here, a = y, b = 2
∴ y2 – 22 = (y + 2)(y – 2)
….[(a2 – b2) = (a + b)(a – b)]
iv. P2 - \(\frac{1}{25}\)
Here a = \(\frac{1}{25},\) b = \(\frac{1}{5}\)