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didieravoaka
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Statement 1:didieravoaka wrote:In the xy plane, what is the x-intercept of line l?
(1) The y-intercept of line l is 3.
(2) Line l has slope -2.
This tells us that the line goes through point (0, 3). It does provide information that can be used to determine what other points are on the line.
Insufficient.
Statement 2:
There are infinite possible lines with slope -2. So a line with slope -2 could pass through the x axis at any point.
Insufficient.
Statements Combined:
We know that line l passes through point (0, 3) and that line l has slope -2. Given these two pieces of information we are now restricted to one line. Given one coordinate of a point on the line we can calculate the other coordinate of that point on the line.
While no further math is needed at this point, for illustrative purposes here is a way to calculate the x-intercept given the information provided by the two statements.
We could use the point slope formula, Slope = (y₂ - y�)/(x₂ - x�).
The y coordinate of the x-intercept is 0. So we could plug in all of the values except the x-intercept, which we could then find.
-2 = (3 - 0)/(0 - x)
-2 = 3/-x
2x = 3
x = 1.5 = the x-intercept of line l
Sufficient.
The correct answer is C.
