Question

If(2a-b)²=42 and a.b=4 whats 4a²+b²=

Answer 1

(2a-b)² = 4a²+b²-4ab = 42.

ab=4

=>4a²+b²-4(4)=42.

=>4a²+b²=58.
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Answer 2

ans-58

${4a}^{2} + {b}^{2} - 4ab = 42$

${4a}^{2} + {b}^{2} - 4 \times {4} = 42$

${4a}^{2} + {b}^{2} - 16 = 42$

${4a}^{2} + {b}^{2} = 42 + 16$

${4a}^{2} + {b}^{2} = 58$