1.
10x²+x-2=0
D=1²-4*10*(-2)=1+80=81
-1+9
x1=_______=8/20=2/5=0.4
20
-1-9
x2=_____=-10/20=-1/2=-0.5
20
⇒10x²+x-2=(x-0.4)(x+0.5)
2. x²+2.1x-1=0
D=4.41-4*1*(-1)=4.41+4=8.41
-2.1+2.9
x1=_________=0.8/2=0.4
2
-2.1-2.9
x2=_________=-5/2=-2.5
2
⇒x²+2.1x-1=(x-0.4)(x+2.5)
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