Question 1018572
1. Sketch a graph of the linear relation 8x + 2y = 24. Explain the procedure.
Solve for "y"::
y = -4x + 12
Plot the points (0,12) and (2,4) and draw a line thru them to see the graph.
{{{graph(400,400,-10,10,-15,15,-4x+12)}}}
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2. Determine the value of B such that the line defined by 8x + By + 92 = 0 passes through the point (-4,12).
Substitute for x and y, and solve for "B":
8*-4 + B*12 + 92 = 0
-32 + 12B + 92 = 0
12b = -60
B = -5
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3. 5. Emma is planning her summer and would like to work enough to travel and buy a new laptop. She can earn $90 each day, after deductions, and she can work a maximum of 40 days in July and August, combined. She expects each day of travel will cost her $150 and the laptop she hopes to buy costs $700. 
a. Write a linear equation that represents the number of days Emma can work and travel and still earn enough for her laptop. (Hint: You can write an equation similar to that shown in the last Example of Lesson 7.2.)
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d <==++ 40
earnings <= 90*40 = 3600
expenses = 700 + 150x
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Equation:: 
y <= 700 + 150x where x is 'number of days'
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4. 6. Tayler claims that when a linear equation is written in general form, 
Ax + By + C = 0, the y-intercept of the corresponding graph is always -C/B.
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/1	a. Show that Tayler’s claim is true for the equation 3x + 5y + 45 = 0.
Answer: y = -45/5 = -9
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/1	b. Explain why -C/A represents the x-intercept. (Hint: What y-value can be substituted into 
Ax + By + C = 0 to determine the x-intercept?) 
Ans:: y = 0
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/1	c. Tayler’s claim is not true for horizontal lines. Explain why. 
Answer: Horizontal lines do not have an x-intercept.  The lines are
parallel to the x-axis.
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/1	d. Suggest a similar rule for the y-intercept. Check the rule using 3x + 5y + 45 = 0.
Let x = 0, then y = -45/5 = -9
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Ax + By + C = 0
For y-int, let x = 0, then y = -C/B
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Answer: 
/1	e. Will the rule always work?
It works if B is not zero.
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Cheers,
Stan H.
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