If a² + b² = 74 and ab = 35, then find a + b.

Solution:

Given, a² + b² = 74 and ab = 35,

Using standard identity : (a + b)² = a² + 2ab + b², we can write

(a + b)² = a² + b² + 2ab

(a + b)² = 74 + (2 × 35)

(a + b)² = 74 + 70

(a + b)² = 144

a + b = √144 = 12

✦ Try This: If x² + y² = 275 and xy = 43, then find x + y

Given, x² + y² = 275 and xy = 43

Using standard identity : (a + b)² = a² + 2ab + b², we can write

(x + y)² = x² + y² + 2xy

(x + y)² = 275 + (2 × 43)

(x + y)² = 275 + 86 = 361

x + y = 19

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

NCERT Exemplar Class 8 Maths Chapter 7 Problem 112

If a² + b² = 74 and ab = 35, then find a + b.

Summary:

If a² + b² = 74 and ab = 35, then a + b is 12

☛ Related Questions:

• Verify: (ab + bc) (ab - bc) + (bc + ca) (bc - ca) + (ca + ab) (ca - ab) = 0
• Verify: (a + b + c) (a² + b² + c² - ab - bc - ca) = a³ + b³+ c³ - 3abc
• Verify: (p - q) (p² + pq + q²) = p³ - q³