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An equation of the line in the XY-plane containing points (0, -9) and (-3, 0) is given as Ax + By = 8. What is the value of 'B'?

a) 3
b) -3
c) 4
d) -4

1 Answer

3 votes

Final answer:

Using the given points, the slope of the line is calculated as -3. Substituting into the slope-intercept form, and rearranging to the standard form 'Ax + By = 8', we find 'B = 1', which is not among the options, indicating a possible error in the provided question.

Step-by-step explanation:

To find the value of 'B' in the equation 'Ax + By = 8' that contains the points (0, -9) and (-3, 0), we can use the two points to determine the slope (m) and then find the equation of the line.

The slope of the line through points (x1, y1) = (0, -9) and (x2, y2) = (-3, 0) is calculated as:

m = (y2 - y1) / (x2 - x1) = (0 - (-9)) / (-3 - 0) = 9 / -3 = -3

Now, using the slope-intercept form (y = mx + b), we can find 'b' (the y-intercept) when x=0:

y = -3x + b

Since the line passes through (0, -9), we substitute x=0 and y=-9:

-9 = -3(0) + b

b = -9

Therefore, the equation of the line is y = -3x - 9. Now we rearrange this to match the given form, Ax + By = 8:

3x + y = -9

Comparing this with Ax + By = 8, it's clear that B = 1, which is not one of the options provided. So there seems to be an error in the question as presented.

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