Question

x+y=13,x-y=3 and
$a - \frac{1}{a} = 3$
a)profe it
${a }^{2} - 3a - 1 = 0$
b)
${x}^{2} + {y}^{2} + xy = what$
c)profe it
${a}^{2} - \frac{1}{ {a}^{2} } = 117$

​

Answer 1

I added this photo for your help. Hope this will be helpful.