A) \[\frac{4}{49}\]
B) \[\frac{49}{4}\]
C) \[\frac{7}{4}\]
D) \[\frac{4}{7}\]
Correct Answer: B
Solution :
Since, 4 is a root of \[{{x}^{2}}+ax+12=0\] \[\therefore \] \[16+4a+12=0\] \[\Rightarrow \] \[a=-7\] Let the roots of the equation \[{{x}^{2}}+ax+b=0\]be \[\alpha \]and \[\alpha .\] \[\therefore \] \[2\alpha =-\alpha \] \[\Rightarrow \] \[\alpha =\frac{7}{2}\] and \[\alpha .\alpha =b\] \[\Rightarrow \] \[{{\left( \frac{7}{2} \right)}^{2}}=b\] \[\Rightarrow \] \[b=\frac{49}{4}\]
You need to login to perform this action.
You will be redirected in
3 sec
