document.write( "Question 197025: If x^(2)+1/x^(2)=4, then what does x^(3)+1/x^(3) equal? \n" ); document.write( "
Algebra.Com's Answer #147730 by RAY100(1637)![]() ![]() ![]() You can put this solution on YOUR website! x^2 +1/x^2 = 4 \n" ); document.write( ". \n" ); document.write( "(x^4 +1) / x^2 =4 \n" ); document.write( ". \n" ); document.write( "x^4 +1 =4x^2 \n" ); document.write( ". \n" ); document.write( "x^4 -4x^2 +1 =0 \n" ); document.write( ". \n" ); document.write( "Let y=x^2 \n" ); document.write( ". \n" ); document.write( "y^2 -4y +1 =0 \n" ); document.write( ". \n" ); document.write( "using quadratic eqn \n" ); document.write( ". \n" ); document.write( "y = { -(-4) +/- sqrt (16-4)} / 2 \n" ); document.write( ". \n" ); document.write( "y = 2 +/- sqrt3 \n" ); document.write( ". \n" ); document.write( "but y=x^2 \n" ); document.write( ". \n" ); document.write( "x^2 =2+/- sqrt3 =2+/- 1.732 = 3.732, .268 \n" ); document.write( ". \n" ); document.write( "x= 1.932, .518 \n" ); document.write( ". \n" ); document.write( "Returning to x^3 + 1/x^3 = ? \n" ); document.write( ". \n" ); document.write( "1.932 ^3 + 1/ 1.932^3 = 7.35 \n" ); document.write( ". \n" ); document.write( "using .518 gives same answer \n" ); document.write( " |