Question
Solve using formula.
$x^2+6 x+5=0$
$x^2+6 x+5=0$
✓
Answer
$x^2+6 x+5=0 $
$\Rightarrow x ^2+6 x +5=0 \text { compare with } ax ^2+ bx + c =0 $
$\Rightarrow a =1, b=6 \text { and } c =5 $
$\therefore b ^2-4 ac =6^2-4(1)(5) $
$=36-20 $
$=16 $
$x=\frac{-b \pm \sqrt{b^2-4 a c}}{2 a} $
$x=\frac{-6 \pm \sqrt{16}}{2 \times 1}=\frac{-6 \pm 4}{2} $
$\Rightarrow x =\frac{-6+4}{2} \text { or } x =\frac{-6-4}{2} $
$\Rightarrow x =-\frac{2}{2} \text { or } x =-\frac{10}{2} $
$\Rightarrow x =-1 \text { or } x =-5$
$\Rightarrow x ^2+6 x +5=0 \text { compare with } ax ^2+ bx + c =0 $
$\Rightarrow a =1, b=6 \text { and } c =5 $
$\therefore b ^2-4 ac =6^2-4(1)(5) $
$=36-20 $
$=16 $
$x=\frac{-b \pm \sqrt{b^2-4 a c}}{2 a} $
$x=\frac{-6 \pm \sqrt{16}}{2 \times 1}=\frac{-6 \pm 4}{2} $
$\Rightarrow x =\frac{-6+4}{2} \text { or } x =\frac{-6-4}{2} $
$\Rightarrow x =-\frac{2}{2} \text { or } x =-\frac{10}{2} $
$\Rightarrow x =-1 \text { or } x =-5$
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