question_answer

If , then x

A)  \[\frac{-9\pm \sqrt{53}}{2}\]                 

B)  \[\frac{-7\pm \sqrt{53}}{2}\]     

C)  \[\frac{-5\pm \sqrt{53}}{2}\]    

D)  None of these

Correct Answer: A

Solution :

[a] \[\Rightarrow 1+6+5x+4x+{{x}^{2}}=0\] \[\Rightarrow {{x}^{2}}+9x+7=0\] \[\therefore x=\frac{-b\pm \sqrt{{{b}^{2}}-4ac}}{2.a}\] \[=\frac{-9\pm \sqrt{81-28}}{2}=\frac{-9\pm \sqrt{53}}{2}\] Hence, option [a] is correct.