Practicing Success
If x-\(\frac{1}{x}\)=6 than x3+\(\frac{1}{{x}^{3}}\) will be? |
234 198 74\(\sqrt {10}\) 86\(\sqrt {10}\) |
74\(\sqrt {10}\) |
If x-\(\frac{1}{x}\)=6 [if x-\(\frac{1}{x}\)=k than x+\(\frac{1}{x}\)=\(\sqrt {{k}^{2}+4}\)] than x+\(\frac{1}{x}\)=\(\sqrt {({6})^{2}+4}\) x+\(\frac{1}{x}\)=\(\sqrt {40}\) = 2\(\sqrt {10}\) x3+\(\frac{1}{{x}^{3}}\) = (2\(\sqrt {10}\))3 - 3×2\(\sqrt {10}\) x3+\(\frac{1}{{x}^{3}}\) = 80\(\sqrt {10}\) - 6\(\sqrt {10}\) = 74\(\sqrt {10}\) |