If 5x^2 -3x-4=0, then what are the values of x?

This will not factor so you can use the quadratic formula
x = [- (-3) +/- sqrt(9 - 4*5*-4) / 10
 = (3 +/-  sqrt 89) / 10  

= 3 + 9.434 / 10  or   3 - 9.434 / 10

=  1.24 ,  -0.64     to the nearest hundredth