Question

Решите две системы уравнений

Answer 1

1
{x²+y²=25
{x+y=7
y=7-x
x²+(7-x)²=25
x²+49-14x+x²-25=0
2x²-14x+24=0
x²-7x+12=0
x1+x2=7 U x1*x2=12
x1=3⇒y1=7-3=4
x2=4⇒y2=7-4=3
(3;4);(4;3)
2
{x+y=22
{lgx-lgy=1⇒lg(x/y)=1⇒x/y=10⇒x=10y
10y+y=22
11y=22
y=2
x=10*2=20
(20;2)