Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

Linear Equations and Slopes

Now that you realize the importance of linear models in describing engineering situations, let

us consider some of the basic characteristics of a linear model. As you know, the basic form of

a line equation is given by

(18.4)

where

by-intercept (the value ofyatx0)

Equation (18.4) is plotted and shown in Figure 18.4. Note positive values were assumed for the

y-intercept and the slope in Figure 18.4. The slope of a linear model shows by how much the

aslope

¢y

¢x



change in y value

change in x value

yaxb

590 Chapter 18 Mathematics in Engineering

T

(°F)

210

160

110

60

10

 40

 40  20 0 20 40 60 80 100

T (°C)

T( C) T( F) T( C) T( F)

 40  40 35 95

 35  31 40 104

 30  22 45 113

 25  13 50 122

 20  4 55 131

 15 5 60 140

 10 14 65 149

 5 23 70 158

032 75 167

541 80 176

10 50 85 185

15 59 90 194

20 68 95 203

25 77 100 212

30 86

■Figure 18.3 The relationship between Fahrenheit and Celsius scales.

Slope 

y

x

y

x

y-intercept

b

y

x

■Figure 18.4 A linear model.

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