Intermediate Algebra
Answer/Discussion to Practice Problems
Tutorial 12: Graphing Equations
Answer/Discussion
to 1a
A(3, 1), B(-2, -1/2), C(2, -2), and D(0,1)
A(3, 1) lies in quadrant I.
B(-2, -1/2) lies in quadrant III.
C(2, -2) lies in quadrant IV.
D(0, 1) lies on the y axis.
(return to problem
1a) |
Answer/Discussion
to 2a
y = 4 x - 10 (0, -10), (1, -14), (-1, -14) |
Let's start with the ordered pair (0, -10).
Which number is the x value and which one
is the y value? If you said x = 0 and y = -10, you are correct!
Let's plug (0, -10) into the equation and see what we get: |
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*Plug in 0 for x and -10 for y
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This is a TRUE statement, so (0, -10) is a solution to the equation y = 4x - 10.
Now, let's take a look at (1, -14).
Which number is the x value and which one
is the y value? If you said x = 1 and y = -14, you are right!
Let's plug (1, -14) into the equation and see what we get: |
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*Plug in 1 for x and -14 for y
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This is a FALSE statement, so (1, -14) is NOT a solution to the
equation y = 4x - 10.
Now, let's take a look at (-1, -14).
Which number is the x value and which one
is the y value? If you said x = -1 and y = -14, you are right!
Let's plug (-1, -14) into the equation and see what we get: |
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*Plug in -1 for x and -14 for y
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Answer/Discussion
to 3a
y = 2 x - 1 |
If we subtract 2x from both sides, then
we can write the given equation as -2x + y = -1.
Since we can write it in the standard form, Ax + By = C, then we have a linear equation.
This means that we will have a line when we go to graph this. |
The three x values I'm going to use are
-1, 0, and 1. (Note that you can pick ANY three x values that
you want. You do not have to use the values that I picked.) You
want to keep it as simple as possible. The following is the chart
I ended up with after plugging in the values I mentioned for x.
x
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y = 2x -
1
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(x, y)
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-1
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y = 2(-1) - 1 = -3
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(-1, -3)
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0
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y = 2(0) - 1 = -1
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(0, -1)
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1
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y = 2(1) - 1 = 1
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(1, 1)
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Answer/Discussion
to 3b
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If we add x squared to both sides
we would end up with .
Is this a linear equation? Note how we have an x squared
as opposed to x to the one power.
It looks like we cannot write it in the form Ax + By = C, because the x has to be to the one power, not squared. So this is not a linear
equation.
However, we can still graph it. |
The seven x values that I'm going to use are -3, -2, -1, 0, 1, 2, and
3. (Note that you can pick ANY x values
that you want. You do not have to use the values that I picked.) You
want to keep it as simple as possible. The following is the chart
I ended up with after plugging in the values I mentioned for x.
x
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(x, y)
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-3
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y = -(-3)^2 = -9
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(-3, -9)
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-2
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y = -(-2)^2 = -4
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(-2, -4)
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-1
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y = -(-1)^2 = -1
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(-1, -1)
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0
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y = -(0)^2 = 0
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(0, 0)
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1
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y = -(1)^2 = -1
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(1, -1)
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2
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y = -(2)^2 = -4
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(2, -4)
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3
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y = -(3)^2 = -9
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(3, -9)
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Answer/Discussion
to 3c
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Do you think this equation is linear or not? It is a tricky problem,
because both the x and y variables are to the one power. However, x is inside the absolute value sign and we can't just take it out of there.
In other words, we can't write it in the form Ax +
By = C. This means that this equation
is not a linear equation. |
The seven x values that I'm going to use are -3, -2, -1, 0, 1, 2, and
3. (Note that you can pick ANY x values
that you want. You do not have to use the values that I picked.) You
want to keep it as simple as possible. The following is the chart
I ended up with after plugging in the values I mentioned for x.
x
|
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(x, y)
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-3
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y = |-3| - 1 = 2
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(-3, 2)
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-2
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y = |-2| - 1 = 1
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(-2, 1)
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-1
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y = |-1| - 1 = 0
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(-1, 0)
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0
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y = |0| - 1 = -1
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(0, -1)
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1
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y = |1| - 1 = 0
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(1, 0)
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2
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y = |2| - 1 = 1
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(2, 1)
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3
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y = |3| - 1 = 2
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(3, 2)
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Last revised on July 3, 2011 by Kim Seward.
All contents copyright (C) 2001 - 2011, WTAMU and Kim Seward.
All rights reserved.
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