graphing linear equations with just one intercept

cougar77d

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Nov 14, 2007
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can anyone help me with my homework?
i need to graph linear equations with just one intercept. like; -4x+5y=o, and y=2x
can anyone help me?
 
What do you mean by "with just one intercept"?

Are you graphing those individually? Easiest way would be to find the x-intercept (by solving for x when y = 0) and the y-intercept (by solving for y when x = 0) and connect them with a line, extending both ways.
 
one intercept as in, through the zero. my teacher said to use whatever numbers i wanted to but i still dont get it.
 
Oh sorry, didn't pay attention to your equations. Both of them only "just have one intercept." So just pick any other point and connect the origin (0,0) with the other point.
 
What do you mean? Lets say for the equation -4x + 5y = 0. Choose any number for x and solve for y to get its corresponding value. This gives you another set of numbers, a coordinate point, which satisfies the equation. Then, connect the two points with a line.
 
so multiply -4 by whatever number i choose then add/subtract it on both sides of the =sign, then divide that by 5?
 
Yep. Solving for y. It's an equation. If you already know the value of x (which you chose) then you just use simple algebra to find the corresponding y value.
 
so lets say i chose 20 to represent x, the number i get out of the 20 over 5 then represent y?
 
Sure but it's essentially the same thing. You're plugging in x = 20 to get some value for y. So if you chose x = 20:

-4(20) + 5y = 0
-80 + 5y = 0
etc. etc.

Usually, you use smaller x values so that your axes are easier to deal with. So maybe x = 5?

Also, if you really want you could put it into the y = mx + b form.
-4x + 5y = 0
5y = -4x
y = -4x/5

Same result either way.
 
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