25x^2=<0<br />x=<0<br />Ответ: (-~;0]
х - 3y = 2
xy+y = 6
__________
x = 2+3y
(2+3y)y+y-6=0
2y+3y^2+y-6=0
3y^2+3y-6=0 /3 -- сократим на три
y^2+y-2=0
D= 1+8 = 9
y1= -1+3/2=1
y2 = -1-3/2 = -2
___________
x=2+3y
x1=2+3*1=5
x2=2+3*(-2)=-4
2х^2-5х-3=0
д=25-4×2×(-3)=25+24=49
х1=(5-7)/2×2=-1/2=-0.5
х2=(5+7)/2×2=3
3-(-0.5)=3.5см это расстояние
4lg|x|-lg²(-x)-4=0
-x>0 →x<0 |x|=-x
lg (-x)=t -t²+4t-4=0 t²-4t+4=(t-2)²=0 t=2
lg(-x)=2 -x=10²=100 x=-100
<span>1)3(4-5xy)(4+5xy)
(12-15xy)(4+5xy)
48+60xy-60xy-75x^2y^2
-75x^2y^2+48
</span><span>2)(x^2-y^3)^2
</span>x^4+y^6
<span>(c+m)^2-(c-m)^2</span>
c^2+2mc+m^2-c^2+2mc-m^2
4mc