=(27-13)(27²+27*13+13²)/(27²+9*39+13²)=14
Тому, що:27*13=9*39.
1.(a^2+b^2)^2=a^4+b^4+2a^2b^2
a^4+b^4=60^2-2a^2b^2
(a+b)^2=a^2+b^2+2ab=60+2ab
2ab=100-60=40
ab=20
a^4+b^4=60^2-2a^2b^2=3600-2*400=3600-800=2800
2.
(x+y)^2=x^2+y^2+2xy=20+16=36
a) a=2, b= -1, c= -6
б) a=4, b=9, c= 20
a) (x-3)(x+3)=0
x1=3, x2= -3
б) x²≠-9
x∈∅
в) x(x-9)=0
x1= 0, x2= 9
г) x(x+9)=0
x1= 0, x2= -9
д) 2x²-x-6=0
D= 1+48= 49
x1= (1+7)/4= 2
x2= (1-7)/4= -1,5
е) 4x²+9x+20=0
D= 81-320
D<0
x∈∅
а) x²+2x-8/x²+4x= (x²-2x+4x-8)/x(x+4)= (x+4)*(x-2)/x(x+4)= (x-2)/x или 1- 2/x
б) y²-y-6/y²+2y= (y²+2y-3y-6)/y(y+2)= (y-3)(y+2)/y(y+2)= (y-3)/y или 1- 3/y