1) (x+2)(x²-2x+4)-x(x+2)(x-2)= (x³+8)-x(x²-4)= x³+8-x³+4x= 8+4x
при x=1, 8+4=12
2) (x²-(x+1)²)+((x+2)²-(x+3)²)=34
(x²-x²-2x-1)+(x²+4x+4-x²-6x-9)=34
(-2x-1)+(-2x-5)=34
-2x-1-2x-5-34=0
-4x-40=0
x= -10
-10; -9; -8; -7
проверяем:
((-10)²-(-9)²)+((-8)²-(-7)²)= (100-81)+(64-49)= 19+15= 34 ч.т.д
X=(11-4y)/3
7x-3y=1
x=(11-4y)/3
7(11-4y)/3-3y=1
x=(11-4y)/3
77/3-37/3y=1
x=(11-4y)/3
-37/3y=1-77/3
x=(11-4y)/3
-37/3y=-74/3
x=(11-4y)/3
y=(-74/3)/(-37/3)
x=(11-4y)/3
y=2
x=(11-4*2)/3
y=2
x=1
y=2
1-cos2x=0
cos2x=1
2x=2πN N∈Z
<span>x=πN N</span>∈Z<span>
ответ </span><span>x=πN n</span>∈Z