Question
Solve the following equation by using formula :
$x^2 + 7x – 7 = 0$
$x^2 + 7x – 7 = 0$
✓
Answer
$
x^2+7 x-7=0
$
Here $a =1, b =7, c =-7$
$
\begin{aligned}
& \therefore D=b^2-4 a c \\
& =(7)^2-4 \times 1(-7) \\
& =49+28 \\
& =77
\end{aligned}
$
$
\begin{aligned}
& \because x=\frac{-b \pm \sqrt{D}}{2 a} \\
& =\frac{-7 \pm \sqrt{77}}{2 \times 1} \\
& =\frac{-7 \pm \sqrt{77}}{2}
\end{aligned}
$
$\therefore x_1=\frac{-7+\sqrt{77}}{2}$ and $x_2=\frac{-7-\sqrt{77}}{2}$
Hence $x=\frac{-7+\sqrt{77}}{2}, \frac{-7-\sqrt{77}}{2}$.
x^2+7 x-7=0
$
Here $a =1, b =7, c =-7$
$
\begin{aligned}
& \therefore D=b^2-4 a c \\
& =(7)^2-4 \times 1(-7) \\
& =49+28 \\
& =77
\end{aligned}
$
$
\begin{aligned}
& \because x=\frac{-b \pm \sqrt{D}}{2 a} \\
& =\frac{-7 \pm \sqrt{77}}{2 \times 1} \\
& =\frac{-7 \pm \sqrt{77}}{2}
\end{aligned}
$
$\therefore x_1=\frac{-7+\sqrt{77}}{2}$ and $x_2=\frac{-7-\sqrt{77}}{2}$
Hence $x=\frac{-7+\sqrt{77}}{2}, \frac{-7-\sqrt{77}}{2}$.
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