[tex]x^2+3x+2\ \textgreater \ 0
a=1
b=3
c=2
delta = b^{2}-4ac = 3^2-4*1*2=9-8=1
x_{1}= \frac{-3+1}{2}= \frac{-2}{2}=-1
x_{2}= \frac{-3-1}{2}= \frac{-4}{2}=-2
[/tex]
[tex]x^2+7x-3x-21=0
x^2+4x-21=0
a=1
b=4
c=-21
delta= b^{2} -4ac= 4^2-4*1*(-21)= 16+84=100
x_{1}= \frac{-4+10}{2}= \frac{6}{2}=3
x_{2}= \frac{-4-10}{2}= \frac{-14}{2}=-7
[/tex]
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