Question : If $x+\frac{1}{x}=2 K$, then what is the value of $x^4+\frac{1}{x^4}$?
Option 1: $16 {K}^4-16 {K}^2-1$
Option 2: $8 {K}^4+4 {K}^2-1$
Option 3: $16 {K}^4-16 {K}^2+2$
Option 4: $16 {K}^4-4 {K}^2-1$
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Correct Answer: $16 {K}^4-16 {K}^2+2$
Solution : $x+\frac{1}{x}=2 K$ $⇒(x+\frac{1}{x})^2=(2 K)^2$ $⇒x^2+\frac{1}{x^2}+2 = 4K^2$ $⇒x^2+\frac{1}{x^2} = 4K^2 -2$ $⇒(x^2+\frac{1}{x^2})^2 = (4K^2 -2)^2$ $⇒x^4+\frac{1}{x^4}+2 = 16K^4-16K^2+4$ $⇒x^4+\frac{1}{x^4} = 16K^4-16K^2+2$ Hence, the correct answer is $16K^4-16K^2+2$.
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Question : If $x+\frac{1}{x}=\mathrm{\frac{K}{2}}$, then what is the value of $\frac{x^8+1}{x^4} ?$
Option 1: $\frac{\mathrm{K}^4-16 \mathrm{~K}^2+32}{16}$
Option 2: $\frac{\mathrm{K}^4-8 \mathrm{~K}^2-36}{32}$
Option 3: $\frac{\mathrm{K}^4-8 \mathrm{~K}^2-32}{16}$
Option 4: $\frac{\mathrm{K}^4-8 \mathrm{~K}^2+32}{16}$
Question : What is the value of $\left(\mathrm{k}+\frac{1}{\mathrm{k}}\right)\left(\mathrm{k}-\frac{1}{\mathrm{k}}\right)\left(\mathrm{k}^2+\frac{1}{\mathrm{k}^2}\right)\left(\mathrm{k}^4+\frac{1}{\mathrm{k}^4}\right)$?
Option 1: $\mathrm{k}^{16}+\frac{1}{\mathrm{k}^{16}}$
Option 2: $\mathrm{k}^{16}-\frac{1}{\mathrm{k}^{16}}$
Option 3: $\mathrm{k}^8-\frac{1}{\mathrm{k}^8}$
Option 4: $\mathrm{k}^8+\frac{1}{\mathrm{k}^8}$
Question : If $x^2+\frac{1}{x^2}=4$, then what is the value of $x^4+\frac{1}{x^4}$?
Option 1: 16
Option 2: 14
Option 3: 12
Option 4: 20
Question : If $2 x+\frac{2}{x}=5$, then the value of $\left(x^3+\frac{1}{x^3}+2\right)$ will be:
Option 1: $\frac{81}{11}$
Option 2: $\frac{81}{7}$
Option 3: $\frac{71}{8}$
Option 4: $\frac{81}{8}$
Question : If $x^{4}+\frac{1}{x^{4}}=16$, then what is the value of $x^{2}+\frac{1}{x^{2}}$?
Option 1: $3 \sqrt{2}$
Option 2: $2 \sqrt{2}$
Option 3: $5 \sqrt{2 }$
Option 4: $4 \sqrt{2}$
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