SOLUTION: solve the polynomial inequality and graph the solution set on a number line. express the solution set in interval notation. 5x^2-3x is greater than or equal to 8

Algebra ->  Inequalities -> SOLUTION: solve the polynomial inequality and graph the solution set on a number line. express the solution set in interval notation. 5x^2-3x is greater than or equal to 8      Log On


   

Question 156337: solve the polynomial inequality and graph the solution set on a number line. express the solution set in interval notation.
5x^2-3x is greater than or equal to 8
Answer by oscargut(2103) About Me  (Show Source):
You can put this solution on YOUR website!
5x^2-3x is greater than or equal to 8
first we find roots of 5x^2-3x-8=0
x+=+%283+%2B-+sqrt%28+%28-3%29%5E2-4%2A5%2A%28-8%29+%29%29%2F%282%2A5%29+ =
x+=+%283+%2B-+%2813%29%29%2F%2810%29+
roots are -1 and 1.6
5x^2-3x is greater than or equal to 8 when
5x^2-3x-8 is greater than or equal to 0
sign of 5x^2-3x-8 is +++++++0- - - - - -0+++++++++
-1 1.6
(press show source to see the sign better)
then Solution set is: (-inf,-1]U[1.6,inf)