how do i find the solution set for f(x)<0 and f(x) greater than or equl to 0 using a graph??

Question

How do I find the solution set: for f(x)<0   and the solution set: f(x)greater than or equal to (symbol) 0 using a graph???

Answer 1

You must remember that f(x)=y (value on the y-axis).

Well, you have an x-axis, and you look at where it intersects with the y-axis. At this point, y=0, and x=0.

As long as you move along the x-axis (to the left or to the right), the y-value will stay 0.
The x-axis is the key.

For every point above it, y>0.

Points where the graph of f(x) intersects with the x-axis: y=0.

Points below the x-axis: y<0.

 

                                        y

                                          ^     y<0 for -1<x<1.3

                            `             |     y>=0 for x<=-1 and x>=1.3

                              `           |

                               `        2--                    `

                                `         |            `

                                 `      1--        `

                                  `       |        `

-----------------------------`---------|---|---|--------------------------> x

                                       `  |   1  `2    3

                                           |`  `