Question

if x+1/x=10 find the value of x2 +1/x2

Answer 1

98
You have to square on both the sides and the expand the variable term on left x and 1/x will get cancelled and 100 - 2 will give 98..
Thank you

Answer 2

$(x + \frac{1}{x} ) {}^{2} = ( {x})^{2} + ( \frac{1}{x} ) {}^{2} + 2 \times x \times \frac{1}{x} \\ \\ (x + \frac{1}{x} ) {}^{2} = {x}^{2} + \frac{1}{ {x}^{2} } + 2 \\ \\ (x + \frac{1}{x} ) {}^{2} - 2 = {x}^{2} + \frac{1}{ {x}^{2} } \\ \\ on \: putting (x + \frac{1}{ {x}^{2} } ) = 10.... \: we \: have \: given \\ \\ (10) {}^{2} - 2 = {x}^{2} + \frac{1}{ {x}^{2} } \\ \\ 100 - 2 = {x}^{2} + \frac{1}{ {x}^{2} } \\ \\ 98 = {x}^{2} + \frac{1}{ {x}^{2} }$