1) х²-8х-9=0
D=64+36=100
x₁ = 8-10 / 2 = -1
х₂ = 8+10 / 2 = 9
х²-8х-9 = (х+1)(х-9)
2) 3х²-8х-3=0
D=64+36=100
х₁ = 8-10 / 6 = -1/3
х₂ = 8+10 / 6 = 3
3х²-8х-3 = 3(х+1/3)(х-3)
1. 4-0,8х - 1,2 х- 4,8 = -2,8 /*10
40-8х-12х-48=-28
20х= 20 /:20
х = 1
3x-4y=0
x=2y+1
3(2y+1)-4y=0
6y+3-4y=0
2y+3=0
2y=-3
y=-3/2=-1.5
x=2*(-1.5)+1=-3+1=-2
(-2: -1.5)
если просто упростить, то у меня вышло так:
<span> ( 5m - 2) ( 5m + 2 ) - ( 5m - 4 )^2 + 10m = 25m^2 - 4 - (25m^2 - 40m + 16) <span>+ 10m </span>= 25m^2 - 4 - 25m^2 + 40m - 16 <span>+ 10m </span>= 50m - 20</span>