1)(x+4)/5-x/3=7
(3(x+4)-5x-15*7)/15=0
-2x-93=0
x= -93/2
2)-x-2+3(x-3)=3(4-x)-3
-x+3x-2-9=12-3x-3
5x=20
x=4
3)3x-4 и 7x+6
3x-4=7x-6
4x=2
x=1/2
4)2x-1 и 3x+9
2x-1=3x+9
x= -10
5) x^2+7=8x
x^2-8x+7=0
x1=1 По теореме Виетта: x1+x2= -b, x1*x2=c
x2=7
6)x^2+3x=18
x^2+3x-18=0
x1= -6
x2=3
7) (x+2)^2=(x-4)^2
x^2+4x+4=x^2-8x+16
12x=12
x=1
8) (x-4)^2+(x+9)^2=2x^2
x^2-8x+16+x^2+18x+81=2x^2
10x+97=0
x= -9,7
1) =a^2+2ab-b^2-2ab-a^2=-b^2
2)= 9b^2-6b+1+8b=9b^2+2b+1
3)=16c^2-6c-16c^2-8c-1=-14c-1
4)(4-a^2)(4-a^2)-a^4=16-8a^2+a^4-a^4=16-8a^2
5) = (x^2-4)(x^2-4)-x^4+16=x^4-8x^2+16-x^4+16=32-8x^2