Х²-7х+12=0
a=1 b=-7 c=12
D=b²-4ac=49-4·1·12=49-48=1
√D=√1=1
x₁=
=
=
=3
x₂=
=
=
=4
Ответ: x₁=3 x₂=4
-x²-5x+6=0
x²+5x-6=0
a=1 b=5 c=-6
D=b²-4ac=25-4·1·(-6)=25+24=49
√D=√49=7
x₁=
=
=
=-6
x₂=
=
=
=1
Ответ: x₁=-6 x₂=1
5х+(3х+2)=(4х-8)+х+20
5х+3х+2=4х-8+х+20
8х+2=5х+12
8х-5х=12-2
3х=10
х=10:3
х=3 1/3
1)(х+4)(х+2)
2)(a-2b)( a-5b)