10-4(2x+5)=6y-13
4y-63=5(4x-2y)+2
4y-63-20x+10y-2=0
14y-65-20x=0
x=0.7y-3.25
3-8x-6y=0
3-8*(0.7y-3.25)-6y=0
3-5.6y+26-6y=0
29-11.6y=0
y=29/11.6y=2.пятых
14*2.5-65-20x=0
-30-20x=0
x=-30/20
x=-1.5
При х = - 0,5 → - 16*(-0,5)^2 + (2,5*-0,5) +25 = - 16*0,25 - 1,25 + 25=
= - 4 - 1,25 + 25 = 25 - 5,25 = 19,75