Question

If a + b = 9 and a2 + b2 = 45, find the value of ab.

Answer 1

Answer:

ab=18

Step-by-step explanation:

(a+b)²=(9)²

a²+b²+2ab=81

45+2ab=81

2ab=81-45

2ab=36

ab=18

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Answer 2

Answer:

ab = 18

Step-by-step explanation:

Given , a² + b² = 45 .... i

and a + b=9 .... ii

Squaring on both sides of equation ii

⟹ (a + b)² = 9²

⟹ a² + b² + 2ab = 81

⟹ 45 + 2ab= 81

⟹ 2ab= 81 - 45

⟹ 2ab = 36

ab = 18