Question

Решите систему уравнений:
х+у=1
х^2-y^2=9

Answer 1

Х^2 - y^2 = 9
( x - y )•( x + y ) = 9
X + y = 1
X - y = 9
2x = 10
X = 5
5 + y = 1
y = - 4
Проверка
5 + ( - 4 ) = 1
1 = 1
5^2 - ( - 4 )^2 = 9
25 - 16 = 9
9 = 9
ОТВЕТ ( 5 ; - 4 )

Answer 2

$left { {x+y=1 } atop {x^2-y^2=9}} right.$

$left { {{{x+y = 1}} atop { x^2 = y^2+9}} right.$

$left { {{{x+y = 1}} atop { (x-y) (x+y) = 9}} right.$

$left { {{{y = 1-x}} atop { x^2-y^2 = 9}} right.$

$left { {{x = 5 } atop { y = -4}} right.$

График внизу если надо