Question

x + y = 3, x2 + y2 = 12, 2xy = ?​

Answer 1

Answer:

${(x + y)}^{2} = {x}^{2} + {y}^{2} + 2xy$

$2xy = {(x + y)}^{2} - {(x}^{2} + {y}^{2} )$

or, 2xy = 9-12 = -3