Verified Answer :
\(x^2 - 4x - 9 = 29 \\ x^2 - 4x - 9 - 29 = 0 \\ x^2 - 4x - 38 = 0 \\ x= \frac{-b \pm \sqrt{ b^{2} -4ac} }{2a}\); where a = 1, b = -4 and c = -38
\(x= \frac{-(-4) \pm
\sqrt{
(-4)^{2} -4 \times 1 \times -38} }{2 \times 1} \\ = \frac{4 \pm \sqrt{ 16 +152} }{2} \\ =\frac{4 \pm \sqrt{ 168} }{2} \\ =\frac{4 \pm
2\sqrt{42} }{2} \\
=2+\sqrt{42} \ or \ 2-\sqrt{42}\\=8.48 \ or \ -4.48\)
Answer:
The two root of the given quadratic equation \(x^2-4x-9=29\) is 8.48 and -4.48 .
Step-by-step explanation:
Consider, the given Quadratic equation, \(x^2-4x-9=29\)
Thus on simplification, we get,
\(x^2-4x-9-29=0 \Rightarrow x^2-4x-38=0\)
We can solve using quadratic formula,
For a given quadratic equation \(ax^2+bx+c=0\) we can find roots using,
\(x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\) ...........(1)
Where, \(\sqrt{b^2-4ac}\) is the discriminant.
Here, a = 1 , b = -4 , c = -38
Substitute in (1) , we get,
\(x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\)
\(\Rightarrow x=\frac{-(-4)\pm\sqrt{(-4)^2-4\cdot 1 \cdot (-38)}}{2 \cdot 1}\)
\(\Rightarrow x=\frac{4\pm\sqrt{168}}{2}\)
\(\Rightarrow x_1=\frac{4+\sqrt{168}}{2} and \Rightarrow x_2=\frac{4-\sqrt{168}}{2}\)
Also, \(\sqrt{168}=12.96\)(approx)
\(\Rightarrow x_1=\frac{16.96}{2} and \Rightarrow x_2=\frac{-8.96}{2}\)
\(\Rightarrow x_1=8.48 and \Rightarrow x_2=-4.48\)
Thus, the two root of the given quadratic equation \(x^2-4x-9=29\) is 8.48 and -4.48 .