College test english 7 docx

CHAPTER 4 • LearningExpress Skill Builders 74

Coordinate Geometry

1. Which line below has no slope?

a. Line A

b. Line B

c. Line C

d. Line D

Let’s review how to tell the slope of a line by looking at

each graph:

Thus, choice d is correct. This line has no slope because

slope  c

c

h

h

a

a

n

n

g

g

e

e

i

i

n

n

x y

There is no change in x for Line D. No change 

zero, which means we would have a zero in the denom￾inator of our slope formula. Zeroes and denominators

do not mix! (Actually dividing by zero is technically

termed undefined, as in you can’t do it!) Therefore, there

is no slope!

Line C is interesting to look at as well. Here there

is a zero slope because there is a zero in the numerator

of the slope formula. There is a zero in the numerator

of the slope formula because there is no change in y.

2. Line AB below contains the points (2, 3) and

(3, 2). What is the equation of line AB?

a. y  x 1

b. y  3x  2

c. y  x  1

d. y  2x  3

The equation of a line is y  mx  b, where m is the

slope of the line (Δ

Δ

x

y

) and b is the y intercept. We are

given 2 points to work with, so first we will determine

the slope.

m = Δ

Δ

x

y

= x

y2

2

y

x

1

1

x

y

1234567

1

2

3

4

5

6

7

-1

-2

-3

-4

-5

-6

-7

-7 -6 -5 -4 -3 -2 -1

(-3,-2)

(2,3)

C

D

X

Y

X

Y

zero

slope

no

slope

A

B

X

Y

X

Y

positive

slope

negative

slope

C

D

X

Y

X

Y

A

B

X

Y

X

Y

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