Question

In the question
If x^2 + y^2 = 14 and xy = 2 1/2, find the value of x-y
Why is it written 2xy?
Please tell

Answer 1

Answer:

$\sf \: ( {x} - {y} )^{2} = {x}^{2} - 2xy + {y}^{2} \\ \\ \sf = 14 - \frac{5}{2} \times 2 \\ \\ = \sf14 - 5 = 9 \\ \\ \bf \: x - y = \sqrt{9} = \underline{ \boxed{ \red{ \bf \: 3}}}$