1) (1+х)(1-х)(1+х^2)=(1-x^2)(1+х^2)=1-x^4
2) 5х^2-3(х+1)(х-1)=5x^2-3(x^2-1)=5x^2-3x^2+3=2x^2+3
10-4(2x+5)=6y-13
4y-63=5(4x-2y)+2
4y-63=5(4x-2y)+2
4y-63-20x+10y-2=0
14y-65-20x=0
x=0.7y-3.25
10-4(2x+5)=6y-13
3-8x-6y=0
3-8*(0.7y-3.25)-6y=0
3-5.6y+26-6y=0
29-11.6y=0
y=29/11.6
y=2.пятых
14y-65-20x=0
14*2.5-65-20x=0
-30-20x=0
x=-30/20
x=-1.5
1) (1+х)(1-х)(1+х²)=(1-х²)(1+х²)=1-х²+х²-х в 4 степени=1-х в 4 степени
2) 5х²-3(х+1)(х-1)=5х²-3(х²-1)=5х²-3х²-3=2х²-3