Question

решите систему
x+y=9,
x2-y2=45.

Answer 1

x+y=9
(x-y)(x+y)=45

(x-y)*9=45
x+y=9
x=9-y
(9-2y)*9=45
9-2y=5
2y=4
y=2
x=9-2=7
Ответ: (7;2)