Question

if
$x {}^{2} + y { }^{2} = 13$
and
$xy = 2$
then find the value of
$x - y = a$
​

Answer 1

Answer:

Given

$x {}^{2} + y {}^{2} = 13 \\ xy = 2 \\ so \: \: \: 2xy = 4 \\ now \: \: \: x {}^{2} + y {}^{2} - 2xy = 13 - 4 \\ (x - y) {}^{2} = 9 \\ x - y = \sqrt{9} \\ x - y = a= + 3 \: or \: - 3$

Answer 2

Answer:

Given

\begin{gathered}x {}^{2} + y {}^{2} = 13 \\ xy = 2 \\ so \: \: \: 2xy = 4 \\ now \: \: \: x {}^{2} + y {}^{2} - 2xy = 13 - 4 \\ (x - y) {}^{2} = 9 \\ x - y = \sqrt{9} \\ x - y = a= + 3 \: or \: - 3\end{gathered}

x

2

+y

2

=13

xy=2

so2xy=4

nowx

2

+y

2

−2xy=13−4

(x−y)

2

=9

x−y=

9

x−y=a=+3or−3