Precalculus
Michael Sullivan
Edition 10
Chapter 1, Section 3.1
30. Suppose that f(x) = 3x + 5 and g(x) = -2x + 15.
A. Solve f(x) = 0
Set 3x + 5 = 0 and solve for x.
2x + 5 = 0
2x = - 5
x = -5/2
B. Solve f(x) < 0.
Set 3x + 5 < 0 and compute.
3x + 5 < 0
3x < - 5
x < -5/3
C. Solve f(x) = g(x).
Set 3x + 5 = -2x + 15 and solve for x.
3x + 5 = - 2x + 15
3x + 2x = 15 - 5
5x = 10
x = 10/5
x = 2
D. Solve f(x) [tex]\ge[/tex] g(x).
Set 3x + 5 [tex]\ge[/tex] -2x + 15 and compute.
3x + 5 [tex]\ge[/tex] - 2x + 15
3x + 2x [tex]\ge[/tex] 15 - 5
5x [tex]\ge[/tex] 10
x [tex]\ge[/tex] 10/5
x [tex]\ge[/tex] 2
E. Graph y = f(x) and y = g(x) and label the point that represents the solution to the equation f(x) = g(x).
Note: Part C above gave us x = 2.
If I let x be 2 for f(x) and g(x), the point representing the solution is (2, 11). The solution is where the two lines meet or cross.
You say?
See attachment.

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