Math CentralQuandaries & Queries


Question from kaylee, a student:

how do you find and graph the intersect of these two equations:
y=2x-4 (and) 2y=x


Hi Kaylee.
I can think of two good methods:

Method 1: Use a graph
Just graph them on the same sheet of paper and see where they intersect.

Method 2: Use algebra
Use the "substitution method" (look it up using our Quick Search if that doesn't mean anything to you) to substitute (2y) in place of x in the first equation and solve for the value of y. Then use that with either equation to find the value of x. This (x, y) is the intersection.

The first method is easier if you like seeing and drawing accurate pictures, but it is less precise. The second is very precise, but you can't "see" the intersection visually.

Hope this helps,
Stephen La Rocque

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