document.write( "Question 155334: solve the polynomial inequality and graph the solution set on a number lines. express the solution set in interval notation. 5x^2-3x is greater than or equal to 8. \n" ); document.write( "
Algebra.Com's Answer #114380 by stanbon(75887)![]() ![]() ![]() You can put this solution on YOUR website! express the solution set in interval notation. 5x^2-3x is greater than or equal to 8 \n" ); document.write( "---------------------- \n" ); document.write( "5x^2-3x-8 >= 0 \n" ); document.write( "------------------ \n" ); document.write( "1st: Solve the EQUALITY: \n" ); document.write( "Factor to get: \n" ); document.write( "5x^2-8x+5x-8 = = \n" ); document.write( "x(5x-8) + (5x-8) = 0 \n" ); document.write( "(5x-8)(x+1) = 0 \n" ); document.write( "x = 8/5 or x = -1 \n" ); document.write( "------------------------- \n" ); document.write( "2nd: \n" ); document.write( "Draw a number line and plot x = -1 and x=(8/5) on it. \n" ); document.write( "Check a test-value in the INEQUALITY from each of the \n" ); document.write( "three number number-line intervals. \n" ); document.write( "------------ \n" ); document.write( "If x = -2 you get 5(-2)^2-(3*-2)-8 > 0; true so solutions in (-inf,-1) \n" ); document.write( "-------- \n" ); document.write( "If x = 0 you get 5(0)^2 - 3*0 -8 >0 ; false so no solution in (-1,8/5) \n" ); document.write( "-------- \n" ); document.write( "If x = 2 you get 5(2)^2 - 3*2 -8 > 0; true, so solutions in (8/5,+inf) \n" ); document.write( "-------- \n" ); document.write( "Final answer: {x|-inf< x <-1} U {x|-1< x <+inf} \n" ); document.write( "============================== \n" ); document.write( "Cheers, \n" ); document.write( "Stan H. \n" ); document.write( " |