simultaneous equation xsquared +ysquared =9, x +y =2

Question

x squared + y squared= 9

x + y =2

Answer 1

Since x+y=2, y=2-x and we substitute for y in the other equation:

x²+(2-x)²=9,

x²+4-4x+x²=9,

2x²-4x=9-4=5, divide through by 2:

x²-2x=5/2,

x²-2x+1=5/2+1=7/2,

(x-1)²=7/2, x-1=±√(7/2), x=1±√(7/2), x=2.8708 or -0.8708.

Therefore y=-0.8708 or 2.8708, respectively.