Solve for xy

[nycmath]

See attachment. Show your work in step by step fashion. Enjoy.

[Eigenvalue]

(x+y)²=18²=324

x²+2xy+y²=324

x+y+(x-y)=18+8=26

2x=26

x=13

y=5

Or:
(13)²+2xy+(5)²=324

169+2xy+25=324

2xy=130

xy=65

[Guest]

[tex]\begin{array}{|l} x + y = 18 \\ x - y = 8 \end{array}[/tex]

We add and subtract the two equations .
[tex]\begin{array}{|l} x + y = 4 \\ x - y = 0 \end{array} \begin{array}{|l} 2x = 26 \\ 2y = 10 \end{array}[/tex]

[tex]\begin{array}{|l} x = 13 \\ y = 5 \end{array}[/tex]

Then xy =65

[Guest]

[tex]\begin{array}{|l} x + y = 18 \\ x - y = 8 \end{array}[/tex]

We add and subtract the two equations .
[tex]\begin{array}{|l} 2x = 26 \\ 2y = 10 \end{array}[/tex]

[tex]\begin{array}{|l} x = 13 \\ y = 5 \end{array}[/tex]

Then xy =65

[nycmath]

(x+y)²=18²=324

x²+2xy+y²=324

x+y+(x-y)=18+8=26

2x=26

x=13

y=5

Or:
(13)²+2xy+(5)²=324

169+2xy+25=324

2xy=130

xy=65

Very cool. Very neat. Very awesome.

[nycmath]

[tex]\begin{array}{|l} x + y = 18 \\ x - y = 8 \end{array}[/tex]

We add and subtract the two equations .
[tex]\begin{array}{|l} x + y = 4 \\ x - y = 0 \end{array} \begin{array}{|l} 2x = 26 \\ 2y = 10 \end{array}[/tex]

[tex]\begin{array}{|l} x = 13 \\ y = 5 \end{array}[/tex]

Then xy =65

Yes, correct.