Question

If (x+y) =7 and xy= -30.Find the value of (x-y)​

Answer 1

$(x + y) = 7 \\ ( {x + y})^{2} = 49 \\ ( {x - y)}^{2} + 4xy = 49 \\ ( {x - y)}^{2} + 4( - 30) = 49 \\ ( {x - y)}^{2} - 120 = 49 \\ ( {x - y)}^{2} = 169 \\ x - y =± 13$