Standard Form

Site: Saylor Academy
Course: GKT101: General Knowledge for Teachers – Math
Book: Standard Form
Printed by: Guest user
Date: Sunday, May 19, 2024, 2:24 PM

Description

When a linear equation is written in standard form, both variables x and y are on the same side of the equation. Watch this lecture series and practice converting equations to standard form.

Graphing a linear equation: 5x+2y=20

Clarifying standard form rules

Converting from slope-intercept to standard form

Graph from linear standard form - Questions

1. Graph 12 x-9 y=36.


2. Graph 3 x+4 y=12.


3. Graph x+3 y=6.


4. Graph -14 x+21 y=84.

Answers

1. This is a linear equation given in standard form: A x+B y=C. A common way of graphing an equation of this form is to find the x- and y-intercepts of the graph.

To find the y-intercept, let's substitute x=0 into the equation and solve for y:

\begin{aligned}
12 x-9 y &=36 \\
12 \cdot 0-9 y &=36 \\
-9 y &=36 \\
y &=-4
\end{aligned}

So the y-intercept is (0,-4).

To find the x-intercept, let's y=0 into the equation and solve for x:

\begin{aligned}
12 x-9 y &=36 \\
12 x-9 \cdot 0 &=36 \\
12 x &=36 \\
x &=3
\end{aligned}

So the x-intercept is (3,0).

We can graph the linear equation using these two points, as shown below:


2. This is a linear equation given in standard form: A x+B y=C. A common way of graphing an equation of this form is to find the x- and y-intercepts of the graph.

To find the y-intercept, let's substitute x=0 into the equation and solve for y:

\begin{array}{r}
3 x+4 y=12 \\
3 \cdot 0+4 y=12 \\
4 y=12 \\
y=3
\end{array}

So the y-intercept is (0,3).

To find the x-intercept, let's y=0 into the equation and solve for x:

\begin{array}{r}
3 x+4 y=12 \\
3 x+4 \cdot 0=12 \\
3 x=12 \\
x=4
\end{array}

So the x-intercept is (4,0).

We can graph the linear equation using these two points, as shown below:


3. This is a linear equation given in standard form: A x+B y=C. A common way of graphing an equation of this form is to find the x- and y-intercepts of the graph.

To find the y-intercept, let's substitute x=0 into the equation and solve for y:

\begin{array}{r}
x+3 y=6 \\
0+3 y=6 \\
3 y=6 \\
y=2
\end{array}

So the y-intercept is (0,2).

To find the x-intercept, let's y=0 into the equation and solve for x:

\begin{array}{r}
x+3 y=6 \\
x+3 \cdot 0=6 \\
x=6
\end{array}

So the x-intercept is (6,0).

We can graph the linear equation using these two points, as shown below:


4. This is a linear equation given in standard form: A x+B y=C. A common way of graphing an equation of this form is to find the x- and y-intercepts of the graph.

To find the y-intercept, let's substitute x=0 into the equation and solve for y:

\begin{aligned}
-14 x+21 y &=84 \\
-14 \cdot 0+21 y &=84 \\
21 y &=84 \\
y &=4
\end{aligned}

So the y-intercept is (0,4).

To find the x-intercept, let's y=0 into the equation and solve for x:

\begin{array}{r}
-14 x+21 y=84 \\
-14 x+21 \cdot 0=84 \\
-14 x=84 \\
x=-6
\end{array}

So the x-intercept is (-6,0).

We can graph the linear equation using these two points, as shown below:

Convert linear equations to standard form - Questions

1. What is y-8=3(x+1) written in standard form?

Choose 1 answer:

A. y-8=3 x+3

B. y=3 x+11

C. -3 x+y-11=0

D. -3 x+y=11


2. What is y=\frac{4}{5} x+2 written in standard form?

Choose 1 answer:

A. -\frac{4}{5} x+y-2=0

B. y=\frac{4}{5}\left(x+\frac{5}{2}\right)

C. 5 y=4 x+10

D. -4 x+5 y=10


3. What is y+5=7(x-8) written in standard form?

Choose 1 answer:

A. x-7 y=-61

B. 7 x+y=-61

C. -7 x+y=-61

D. x+7 y=-61


4. What is y=-\frac{3}{10} x-8 written in standard form?

Choose 1 answer:

A. 10 x+3 y=-80

B. 10 x-3 y=-80

C. -3 x+10 y=-80

D. 3 x+10 y=-80

Answers

1. D. -3 x+y=11

Standard linear equations are in the general form A x+B y=C where A, B, and C are constants.

Usually, A, B, and C are integers.

y-8=3(x+1)
y-8=3 x+3 Distribute.
y=3 x+11 Collect constants.
-3 x+y=11 Bring to standard form.

y-8=3(x+1) written in standard form is -3 x+y=11.


2. D. -4 x+5 y=10

Standard linear equations are in the general form A x+B y=C where A, B, and C are constants.

Usually, A, B, and C are integers.

y=\frac{4}{5} x+2
5 y=4 x+10 Multiply by denominator.
-4 x+5 y=10 Bring to standard form.


y=\frac{4}{5} x+2 written in standard form is -4 x+5 y=10.


3. C. -7 x+y=-61

Standard linear equations are in the general form A x+B y=C where A, B, and C are constants.

Usually, A, B, and C are integers.

y+5=7(x-8)
 y+5=7 x-56 Distribute.
y=7 x-61 Collect constants.
-7 x+y=-61 Bring to standard form.


y+5=7(x-8) written in standard form is -7 x+y=-61.


4. D. 3 x+10 y=-80

Standard linear equations are in the general form A x+B y=C where A, B, and C are constants.

Usually, A, B, and C are integers.

y=-\frac{3}{10} x-8
10 y=-3 x-80 Multiply by denominator.
3 x+10 y=-80 Bring to standard form.


y=-\frac{3}{10} x-8 written in standard form is 3 x+10 y=-80.