# Week 10-solving Quadratic inequalities in one variable

The formula that we learned

$ax^2 +bx+c<0$ $ax^2 +bx+c>0$ $ax^2 +bx+c<(=)0$ $ax^2 +bx+c>(=)0$

where a, b, and c are constants and a not =0

Ex:

The solution of the quadratic inequality

$x^2 -2x-3>0$ is the value of x for which y>0 ; that is ,the values of x for which the graph is above the x -axis.Visualize the shadow of the graph on the x-axis.

so we first have to factor this formula

$x^2 -2x-3=0$

(x-3)(x+1)=0

ok, so we can get the value of x for equal to zero

x=3,x=-1

and because  y>0

so the part of y>0 are

-1>x>3