Quick Homework Help

# how do I solve the quadratic inequality with a graph? ⚑ Flag

by Noemi016 at October 29, 2010

Identify the range of y, the vertex, the highest or lowest point, depending on a positive or negative x value.

fabianscorpio October 29, 2010

You need to first solve the related equation to find the x-intercepts of the graph.  If your leading coefficient (or a) is positive then sketch a parabola opening upward and crossing through the two points you just found.  If a is negative, then do the same with a downward opening parabola.  Now look back to your original inequality and make it so that one side of the inequality is zero.  If your function is greater than (or equal to) zero, then you look at what part of the function contains positive y values (or where it is above the x-axis).  If the function is less than (or equal to) zero, then look at where the graph is below the x-axis.  If the part you're looking at contains the function's vertex, then you have an "and" statement with x between your two intercepts.  If the part you're looking at contains the ends of the function's graph, then you have an "or" statement with x less (or equal to) your leftmost intercept "or" x greater than (or equal to) your rightmost intercept.

Bill201 October 29, 2010

Stoichiometry October 29, 2010

Someone said what I was going to say. Sorry buddy.

ChromeRedCat October 29, 2010

what you do is graph the function with a dotted line if its only greater than or less than or with a solid line if its also equal to.Then you just plot a point on the inside or outside of the graph and shade the area where it works

Car...los... October 30, 2010

I'd say, but it's already listed.  Good luck!

yankeekid October 30, 2010

What Carlos said is wrong  ...That's how you graph an inequality.  When solving an inequality by graphing, there is no need for a dashed or solid boundary parabola.  You would only shade along the x-axis.  If it's an "and" statement then you shade between your intercepts  Your intercepts would need an open circle for less than or greater than, or a closed dot for less (or greater) than or equal to.  If it's an "or" statement, then you do the same with your intercepts and draw shaded arrows along the x-axis which point outwards to where your inequality is true.  It would look like shading a linear inequality along a number line, except your number line is now the x-axis.

Bill201 October 30, 2010