Answer:
[tex]x = \frac{7 + \sqrt{85} }{2} \:\: or \:\: \frac{7 - \sqrt{85} }{2}[/tex]
Step-by-step explanation:
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FACTS TO KNOW BEFORE SOLVING :-
Quadratic Formula :-
For a quadratic equation ax² + bx + c = 0 , by using quadratic formula the roots of the equation are :-
[tex]x = \frac{-b + {\sqrt{b^2 - 4ac} } }{2a} \:\: or \:\: \frac{-b - \sqrt{b^2 - 4ac} }{2a}[/tex]
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Lets solve the equation x² - 7x - 9 = 0 by quadratic formula.
[tex]=> x = \frac{-(-7) + \sqrt{(-7)^2 - 4 \times 1 \times (-9)} }{2 \times 1} \:\: or \:\: \frac{-(-7) - \sqrt{(-7)^2 - 4 \times 1 \times (-9)} }{2 \times 1}[/tex]
[tex]=> x = \frac{7 + \sqrt{85} }{2} \:\: or \:\: \frac{7 - \sqrt{85} }{2}[/tex]
