Question

A straight line joins the points(-1, 1) and (3, 9). Its x intecept is​

Answer 1

Answer:

The slope of a line is often called "rise over run" because it is the increase in y-values divided by the increase in x-values.  The x-intercept is the point where y=0.

 

Two points determine a line.  The points (-1,1) and (3,9) determine a line with the slope (9-1)/(3-(-1)) = 8/4 = 2.  That means the equation of the line looks like y=2x + b where b is the y-intercept (the place where x=0).

 

Now, plug either point into that equation to determine b.

          9 = 2(3) + b

          3 = b

So, y=2x + 3   and find x when y=0:

     0 = 2x + 3

    -3 = 2x

    -3/2 = x

 

The x-intercept is (-3/2, 0).

Step-by-step explanation: