117998
If \(i=\sqrt{-1}\) and \(\left(\frac{1+1}{1-i}\right)^n=1\), then the least positive integral value of \(n\) is
1 2
2 4
3 1
4 3
Explanation:
B We have, \(\left(\frac{1+\mathrm{i}}{1-\mathrm{i}}\right)^{\mathrm{n}}=1\) \(\left(\frac{1+i}{1-i} \times \frac{1+i}{1+i}\right)^n=1\) \(\left(\frac{1-1+2 i}{1+1}\right)^n=1\) \(\left(\frac{2 \mathrm{i}}{2}\right)^{\mathrm{n}}=1 \Rightarrow \mathrm{i}^{\mathrm{n}}=1 \quad\left\{\begin{array}{c}\because \mathrm{i}^2=-1 \\ \mathrm{i}^4=1\end{array}\right\}\) \(n\) should be multiple of 4 the least positive integral value of \(n\) is 4 .
JCECE-2019
Complex Numbers and Quadratic Equation
117999
\(\left[\frac{-1+\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}+\left[\frac{-1-\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}\) is equal to
117998
If \(i=\sqrt{-1}\) and \(\left(\frac{1+1}{1-i}\right)^n=1\), then the least positive integral value of \(n\) is
1 2
2 4
3 1
4 3
Explanation:
B We have, \(\left(\frac{1+\mathrm{i}}{1-\mathrm{i}}\right)^{\mathrm{n}}=1\) \(\left(\frac{1+i}{1-i} \times \frac{1+i}{1+i}\right)^n=1\) \(\left(\frac{1-1+2 i}{1+1}\right)^n=1\) \(\left(\frac{2 \mathrm{i}}{2}\right)^{\mathrm{n}}=1 \Rightarrow \mathrm{i}^{\mathrm{n}}=1 \quad\left\{\begin{array}{c}\because \mathrm{i}^2=-1 \\ \mathrm{i}^4=1\end{array}\right\}\) \(n\) should be multiple of 4 the least positive integral value of \(n\) is 4 .
JCECE-2019
Complex Numbers and Quadratic Equation
117999
\(\left[\frac{-1+\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}+\left[\frac{-1-\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}\) is equal to
117998
If \(i=\sqrt{-1}\) and \(\left(\frac{1+1}{1-i}\right)^n=1\), then the least positive integral value of \(n\) is
1 2
2 4
3 1
4 3
Explanation:
B We have, \(\left(\frac{1+\mathrm{i}}{1-\mathrm{i}}\right)^{\mathrm{n}}=1\) \(\left(\frac{1+i}{1-i} \times \frac{1+i}{1+i}\right)^n=1\) \(\left(\frac{1-1+2 i}{1+1}\right)^n=1\) \(\left(\frac{2 \mathrm{i}}{2}\right)^{\mathrm{n}}=1 \Rightarrow \mathrm{i}^{\mathrm{n}}=1 \quad\left\{\begin{array}{c}\because \mathrm{i}^2=-1 \\ \mathrm{i}^4=1\end{array}\right\}\) \(n\) should be multiple of 4 the least positive integral value of \(n\) is 4 .
JCECE-2019
Complex Numbers and Quadratic Equation
117999
\(\left[\frac{-1+\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}+\left[\frac{-1-\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}\) is equal to
117998
If \(i=\sqrt{-1}\) and \(\left(\frac{1+1}{1-i}\right)^n=1\), then the least positive integral value of \(n\) is
1 2
2 4
3 1
4 3
Explanation:
B We have, \(\left(\frac{1+\mathrm{i}}{1-\mathrm{i}}\right)^{\mathrm{n}}=1\) \(\left(\frac{1+i}{1-i} \times \frac{1+i}{1+i}\right)^n=1\) \(\left(\frac{1-1+2 i}{1+1}\right)^n=1\) \(\left(\frac{2 \mathrm{i}}{2}\right)^{\mathrm{n}}=1 \Rightarrow \mathrm{i}^{\mathrm{n}}=1 \quad\left\{\begin{array}{c}\because \mathrm{i}^2=-1 \\ \mathrm{i}^4=1\end{array}\right\}\) \(n\) should be multiple of 4 the least positive integral value of \(n\) is 4 .
JCECE-2019
Complex Numbers and Quadratic Equation
117999
\(\left[\frac{-1+\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}+\left[\frac{-1-\sqrt{(-3)}}{2}\right]^{3 \mathrm{n}}\) is equal to