| Case Study : Q. 26 to 30 |
| Ramesh was asked by one of his friends to find the polynomial whose zeroes are \[\frac{-2}{\sqrt{3}}\] and \[\frac{\sqrt{3}}{4}\]. He obtained the polynomial as shown below: |
| Let \[\alpha =\frac{-2}{\sqrt{3}}\] and \[\alpha =\frac{\sqrt{3}}{4}\] |
| \[\Rightarrow \,\,\,\,\,\,\,\alpha +\beta =\frac{-2}{\sqrt{3}}+\frac{\sqrt{3}}{4}=\frac{-8+1}{4\sqrt{3}}=\frac{-7}{4\sqrt{3}}\] |
| \[\Rightarrow \,\,\,\,\,\,\,\alpha \beta =\frac{-2}{\sqrt{3}}\times \frac{\sqrt{3}}{4}=\frac{-1}{2}\] |
| Required polynomial \[={{x}^{2}}-(\alpha +\beta )x+\alpha \beta \] |
| \[={{x}^{2}}-\left( \frac{-7}{4\sqrt{3}} \right)x+\left( \frac{-1}{2} \right)\] |
| \[={{x}^{2}}+\frac{7x}{4\sqrt{3}}-\frac{1}{2}\] |
| \[=4\sqrt{3}{{x}^{2}}+7x-2\sqrt{3}\] |
| His another friend Kavita pointed out that the polynomial obtained is not correct. |
| Based on the above situation, answer the following questions: |
A) Yes
B) No
C) Can't say
D) None of these
Correct Answer: A
Solution :
| Given, \[\alpha =\frac{-2}{\sqrt{3}}\]and \[\beta =\frac{\sqrt{3}}{4}\] |
| \[\alpha +\beta =\frac{-2}{\sqrt{3}}+\frac{\sqrt{3}}{4}=\frac{-8+3}{4\sqrt{3}}=\frac{-5}{4\sqrt{3}}\] |
| \[\alpha \beta =\frac{-2}{\sqrt{3}}\times \frac{\sqrt{3}}{4}=-\frac{1}{2}\] |
| Yes, because value of \[(\alpha +\beta )\] calculated by Anirudh is incorrect. |
| So, option [a] is correct. |
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