Question

if a-b = 6 and ABC = 3 find a2 + b²

Answer 1

squaring on both sides
a²+b²-2ab=36
a²+b²=36+6
=42

Answer 2

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Here is your answer
a - b = 6. and ab = 3

Now
$(a - b) {}^{2} = 6 {}^{2} \\ a {}^{2} + {b}^{2} - 2ab = 36 \\ {a}^{2} + {b }^{2} - 2 \times 3 = 36 \\ a {}^{2} + {b}^{2} = 36 + 6 \\ {a}^{2} + {b}^{2} = 42$

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