Question

if 2a+b=9 and ab = -4,then find value of 4a square + b square

Answer 1

Given,
2a+b = 9 ———>1
ab = (-4) ———>2
(2a+b)² = 4a² + b² + 2ab
=>(9)² = 4a² + b² + 2 x (-4) [From eq. 1&2]
=>81 = 4a² + b² + (-8)
=>4a² + b² = 81 - (-8)
=>4a² + b² = 81 + 8
=>4a² + b² = 89.




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Answer 2

Answer:

answer= 89

Step-by-step explanation:

Given,

2a+b = 9 ———>1

ab = (-4) ———>2

(2a+b)² = 4a² + b² + 2ab

=>(9)² = 4a² + b² + 2 x (-4) [From eq. 1&2]

=>81 = 4a² + b² + (-8)

=>4a² + b² = 81 - (-8)

=>4a² + b² = 81 + 8

=>4a² + b² = 89.

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