(х+2)(х-2)+(2х-3)²=(1-5х)(4-х)
x²-4+4x²-12x+9=4-x-20x+5x<span>²
5x</span>²-12x²+5=4-21x+5x<span>²
5x</span>²-12x+5-4+21x-5x<span>²=9x+1
ОТВЕТ: 9x+1</span>
1.
x+y=12
<span>x-y=2
x=2+y
2+y+y=12
x=2+y
2+2y=12
x=2+y
2y=10
x=2+y
y=5
x=7
y=5
2.
</span>(x+y² =9,
(x+2y =9
Г) (5; 2)
Проверка:
5+2²=9
5+2*2=9
9=9
9=9
3.
(3х+у=4,
<span>(х</span>²<span>-у=14
</span>
y=4-3x
x²-4+3x=14
y=4-3x
x²+3x-18=0
D=3²+4*18=81=9²
x₁=(-3-9)/2=-6 y₁=4+18=22
x₂=(-3+9)/2=3 y₂=4-9=-5
Ответ будет -1
с:
.........................
X-7=0⇒x=7
-4x-1=0⇒x=-1/4
-x-3=0⇒x=-3
5x-6=0⇒x=1,2
+ _ + _ +
-------------(-3)------------(-1/4)-----------(1,2)-----------[7]-----------------
x∈(-∞;-3) U (-1/4;1,2) U [7;∞)