For any graphable equation, the software first manipulates it into its standard form before graphing; for a linear equation, that form is "y=mx+b" where the slope "m" may then be determined by inspecting the equation (for example, in the equation "y=-2x+4" "-2" is the correct value for "m"). For a parabolic equation, the standard form is y = a(x - h)^2 + k, from which direction (polarity of "a") and axis of symmetry (value of "h"), etc. may be determined by inspection. 

So knowing that the y-intercept is -4, that means x=0 and the point (0,-4) are the x and y values for the y-intercept. 

Let y=0 and solve for x, to find the x-intercept:

Click to see all the steps

So the x-intercept is 4/7. 

Some of the linear equations may be better examined through Algebrator's desktop software.  To help you clearly understand our desktop software and how appropriate it may be for your needs, please use one of the following links to obtain a free trial of the program:

Windows: http://www.softmath.com/tr/alg51win-tr-en.exe

Mac: http://www.softmath.com/tr/alg51mac-tr-en.dmg