Rewriting Equations and Formulas

1
Rewriting Equations and Formulas

• J. Ferguson
• Ms. Gatlin 2nd period

2
How to use this tutorial

• During this tutorial, you may use buttons you are
  unfamiliar with.
• This button takes you to the next slide when
  clicked on.
• This button takes you to the previous slide when
  clicked.
• This button takes you to the last slide viewed
  when it is clicked.

3
Rewriting an equation with more than one variable

• Many equations involve more than one variable.
  You can solve such an equation for one of its
  variables. To show you how to do this, I will use
  the equation 7X-3Y8
• To start of this equation, you write the original
  equation. 7X-3Y8
• Next, you subtract 7X from each side, which moves
  the 7X to the other side of the equation. -3Y
  -7X8
• Lastly, you divide each side by -3 so that the Y
  is left alone.
• Y 7/3x-8/3
• After dividing both sides by -3 that is the
  answer that you should get.

4
Equations with more than one variable

• Given the equation 2x 5y 4, use each method
  below to find y when x -3, -1, 2, and 6.
• Method 1 Substitute x -3 into 2x 5y 4 and
  solve for y. repeat this process for the other
  values of x.
• Method 2 Solve 2x 5y 4 for y. Then evaluate
  the resulting expression for y using each of the
  given values of x.

5
Example 1

• Solve the equation for y.
• 4x 8y 17
• y 1/4x 17/8
• y 1/4x 2 1/8
• y 2x 17/8

A
B
C
6
Example 2

• Solve the equation for y.
• 5x 3y 9
• X -5/3y 3
• X -5/3y 3/9
• X 5/3y 3/9

A
B
C
7
Congratulations!

• I think you have the equation part, now lets try
  the formula section!

8
Common Formulas

• Variables
• D distance, r rate, t time
• I interest, P principal, r rate, t time
• F degrees Fahrenheit, C degrees Celsius
• A area, b base, h height
• A area, l length, w width
• P perimeter, l length, w width
• A area, r radius
• C circumference, r radius

• Formula
• D rt
• I Prt
• F 9/5C 32
• A 1/2bh
• A lw
• P 2l 2w
• A 3.14r squared
• C 2 (3.14r)

Distance Simple Interest Temperature Area of
Triangle Area of Rectangle Perim. Of
triangle Area of Circle Circumference of Circle
9
Rewriting Common Formulas

• When rewriting a formula, you always try to get
  one of the variables that is asked to be solved
  for by itself. A good example would be using the
  perimeter formula.
• Solve for w.
• P 2l 2w Write the perimeter formula
• P 2l 2w Subtract 2l from each side
• P 2l w Divide each side by two
• 2

10
Example 1

• Try solving the problem
• Volume of a Cone
• Solve for h V 1/3(3.14)r2h
• (r2 means r squared)(3.14 pie)
• h 3V
• 3.14r2
• h 3vr2
• h 3v3.14r

A
B
C
11
Example 2

• Try solving the problem
• Investment at simple interest
• Solve for P I Prt
• P Irt
• P Ir
• P I
• rt

A
B
C
12
Congratulations!

• I think that have got it! You have passed the
  Rewriting Equations and Formulas tutorial!

13
Where I got my information

• McDougal Littell Algebra 2 textbook
• Section 1.4