System 1:
Let
,
,
,
, then
System 2:
Multiply the 2nd equation by 3
Add the two equations:
Factor the left side:
Take cube roots of both sides:
Eq. 1
Factor the left side of the 1st equation in system 2
Use Eq. 1 to substitute 9 for (x+y)
, reduce 183/9 to 61/3
Eq. 2
Square both sides of Eq. 1:
Eq. 3
Multiply Eq. 2 by -1 and add Eq. 3
Substitute
for xy in in Eq. 2
Since x²=a and y²=b,
Edwin