Problem: Find the valu of x$^{6}$+$\frac{1}{x^{6}}$, if x+$\frac{1}{x}$ =3
View all: SONALI BANK LTD (OFFICER) WRITTEN QUESTION (MATH) SOLVE | 2018
Correct Answer: 322
Explanation:
$(x+\frac{1}{x})$ = 3
Now, $(x^{6}+\frac{1}{x^{6}})=(x^{2})^{3}+(\frac{1}{x^{2}})^{3}$
= $(x^{2}+\frac{1}{x^{2}})^{3}- 3\times x^{2}\times \frac{1}{x^{2}}(x^{2}+\frac{1}{x^{2}})$
= $(x^{2}+\frac{1}{x})^{3}-3(x^{2}+\frac{1}{z^{2}})$
= {$(x+\frac{1}{x})^{2}-2\times x\times \frac{1}{x}$}$^{3}$-3{${(x+\frac{1}{x})^{2}}-2\times x\times \frac{1}{x}$}
= {$(3)^{2}-2$}$^{3}$-3{(3)$^{3}$-2}
= (9-2)$^{3}$-3(9-2)
= (7)$^{3}$-3×7
=343-21=322