If $x = 2 + \sqrt{3},$ then find the value of $x^{2} + \frac{1}{x^{2}}$ and $x^{3} + \frac{1}{x^{3}}.$

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Given $x = 2 + \sqrt{3}.$
First,find $\frac{1}{x} = \frac{1}{2 + \sqrt{3}}.$
Rationalizing the denominator: $\frac{1}{2 + \sqrt{3}} \times \frac{2 - \sqrt{3}}{2 - \sqrt{3}} = \frac{2 - \sqrt{3}}{4 - 3} = 2 - \sqrt{3}.$
Now,$x + \frac{1}{x} = (2 + \sqrt{3}) + (2 - \sqrt{3}) = 4.$
To find $x^{2} + \frac{1}{x^{2}},$ use the identity $(x + \frac{1}{x})^{2} = x^{2} + \frac{1}{x^{2}} + 2.$
$4^{2} = x^{2} + \frac{1}{x^{2}} + 2 \implies 16 = x^{2} + \frac{1}{x^{2}} + 2 \implies x^{2} + \frac{1}{x^{2}} = 14.$
To find $x^{3} + \frac{1}{x^{3}},$ use the identity $(x + \frac{1}{x})^{3} = x^{3} + \frac{1}{x^{3}} + 3(x + \frac{1}{x}).$
$4^{3} = x^{3} + \frac{1}{x^{3}} + 3(4) \implies 64 = x^{3} + \frac{1}{x^{3}} + 12 \implies x^{3} + \frac{1}{x^{3}} = 52.$
Thus,the values are $14$ and $52.$

Explore More

Similar Questions

Insert a rational number and an irrational number between the following: $\sqrt{2}$ and $\sqrt{3}$

Difficult
View Solution

Express the following in the form $\frac{p}{q},$ where $p$ and $q$ are integers and $q \neq 0.$
$0.5 \overline{7}$

Rationalise the denominator in each of the following and hence evaluate by taking $\sqrt{2}=1.414, \sqrt{3}=1.732$ and $\sqrt{5}=2.236,$ up to three decimal places.
$\frac{1}{\sqrt{3}+\sqrt{2}}$

If $x = 3 + 2\sqrt{2}$,then find the value of $x^{2} + \frac{1}{x^{2}}$ and $x^{3} + \frac{1}{x^{3}}$.

Difficult
View Solution

Classify the following numbers as rational or irrational with justification:
$(i)$ $\sqrt{\frac{9}{27}}$
$(ii)$ $\frac{\sqrt{28}}{\sqrt{343}}$

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo