Question

If (a-b)=4 and ab = 23 find the value of a-b
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Answer 1

$a + b = \sqrt{ ({a - b)}^{2} + 4ab } \\ = \sqrt{ {4}^{2} + 4 \times 23} \\ = \sqrt{16 + 92} \\ = \sqrt{108} \\ = 6 \sqrt{3}$