Simplify: [(7/9)a + (9/7)b]² - ab

Solution:

Given, [(7/9)a + (9/7)b]² - ab

Using standard identity: (x+ y)² = x² + 2xy + y²

Here, x = (7/9)a and y = (9/7)b

[(7/9)a + (9/7)b]² - ab ⇒ [(7/9)a]² + 2((7/9)a) ((9/7)b) + [(9/7)b]² - ab

= (49a²/81) + 2ab + (81b²/49) - ab

= (49a²/81) + ab + (81b²/49)

✦ Try This: Simplify: [(4/9)p + (9/4)q]² - 2pq

Given,Simplify: [(4/9)p + (9/4)q]² - 2pq

Using standard identity: (a + b)² = a² + 2ab + b²

Here, a = (4/9)p and b = (9/4)q

=(16p²/81) + 2pq + (81q²/16) - 2pq

= (16p²/81) + (81q²/16)

☛ Also Check: NCERT Solutions for Class 8 Maths Chapter 9

NCERT Exemplar Class 8 Maths Chapter 7 Problem 84(iii)

Simplify: [(7/9)a + (9/7)b]² - ab

Summary:

Simplifying [(7/9)a + (9/7)b]² - ab, we get (49a²/81) + ab + (81b²/49)

☛ Related Questions:

• Simplify: [(3/4)x - (4/3)y]² + 2xy
• Simplify: (1.5p + 1.2q)² - (1.5p - 1.2q)²
• Simplify: (2.5m + 1.5q)² + (2.5m - 1.5q)²