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Cogito

Grade 8 Math · Chapter 3 · Lesson 2

Practice Worksheet

y = mx + b

The slope and where it starts.

10 problems · about 19 minutes · 8.EE.B.6, 8.F.A.3

NameDate

Figure — use these to answer the problems

Change m and b separately. Watch which one tilts and which one lifts.
-10-10-5-5551010
y = 2x + 3
Slope m2
Intercept b3
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

2 problems

  1. From “Why Slope Is the Same Everywhere”

    Rise 12, run 4. Slope?

    Answer

  2. From “Angle-Angle Similarity”

    Angles 25° and 95°. What is the third?

    Answer

Warm Up

Straightforward practice. Get the method working first.

4 problems

  1. y = 3x − 4. What is y when x = 6?

    Answer

  2. In y = mx + b, what does b tell you?

    • Where the line crosses the vertical axis.
    • How steep the line is.

  3. y = 2x + 7. What is the slope?

    Answer

  4. y = 2x + 7. What is y when x = 0?

    Answer

Build It Up

The same ideas with more to keep track of.

2 problems

  1. y = −x + 4. What is y when x = 3?

    Answer

  2. y = 5x. Does it pass through the origin?

    • Yes, b is 0.
    • No.

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

2 problems

  1. The Value

    y = 4x + 3. What is y when x = 5?

    Answer

  2. The Intercept

    y = 7x − 2. What is y when x = 0?

    Answer