Slope-Intercept Practice

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Question 1
Given that the Slope-Intercept form for an equation of line is:

                              y = mx + b

Which of the line below (labeled A, B, C and D) is the graph of:
                              
                               y = x -2                   
Multiple lines with the label A, B,C, D

Answer

Select and check your answer...
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A. Line A
B. Line B
C. Line C
D. Line D
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Step by Step Solution 

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Step 1
To solve this question, we should know that:

             m = slope of the line
             b = y-intercept of the line

A line will slant upwards to the right for m > 0 and the slants upwards to the left for
m < 0.

You can look at the pictures below to understand better.
slope-intercept form of a line
positive slope
negative slope
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Step 2
Next, y-intercept is the y-coordinate of the point that the line crosses the y-axis.

The picture on the right will help you to understand this better.
x and y intercepts
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Step 3
With what you have learned in Step 1 and Step 2, we can start to label the slope and y-intercept for all the lines as shown in the picture.

Now, from the given equation:
       
               y = x -2
=>          y = 1x -2

We can see that:

   slope =  m = 1  (hence, m >0)
   y-intercept =  b = -2


From this, only line C has
m > 0 and y-intercept = -2.

Clearly, the answer is C.
 
lines labeled with slope and y-intercept
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