If A2 + B2 = 34 And Ab = 12; Find : 7(A - B)2 - 2(A + B)2

If a² + b² = 34 and ab = 12; find : 7(a - b)² - 2(a + b)²

Sum

a² + b² = 34, ab= 12

(a + b)² = a² + b² + 2ab
= 34 + 2 x 12 = 34 + 24 = 58

(a - b)² = a² + b² - 2ab
= 34 - 2 x 12 = 34- 24 = 10\

7(a - b)² - 2(a + b)²= 7 x 10 - 2 x 58 = 70 - 116 = - 46

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Chapter 4: Expansions - Exercise 4 (D) [Page 64]

Chapter 4 Expansions
Exercise 4 (D) | Q 6.2 | Page 64

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