(3x-y)(9x²+y)(3x+y) = ((3x-y)(3x+y))(9x²+y) = (9x²-y)(9x²+y)= 81x⁴-9x²y+9x²y-y²= 81x⁴-y²
А. 4х^4*(-2х^2)^3=2х^8*(-2х^6)=-(2х^14)
б.(3х-1)(3х+1)+(3х+1)^2=9х^2+3х-3х-1+9х^2+1=9х^4
7x^2 = 5x
7x^2-5x=0
x(7x-5)=0
x=0 или x=5/7
7=28x^2
x^2=28/7
x^2=4
x1=2
x2=-2
x^2- 4/9 =0
x^2 = 4/9
x1=2/3
x2=-2/3
A1=10
d=2
S45=(2a1+44d)*45/2=(20+88)*45/2=108*45/2=54*45=2430