hello :
x²+y²=25 ...(1)
, 2x+y=10 ....(2)
by (2) : y = 10 -2x
subsct in (1) :
x² + ( 10-2x)² = 25
x² +100 - 20x +4x² = 25
5x²-20x +75 = 0
x² - 4x +15 = 0
(x+3)(x-5) =0
x+3 =0 or x-5 = 0
x = -3 or x = 5
if x= -3 y = 10 -2(-3) =16
if x =5 y = 10-2(5) = 0
two solutions : (-3 , 16) , (5 , 0 )
