A-CED Rearranging equations to solve for desired variables

Alignment: HSA-CED.A.4

HSA: Algebra

Domain: HSA-CED: Creating Equations

Cluster: Create equations that describe numbers or relationships

Standard: Rearrange formulas to highlight a quantity of interest, using the same reasoning as in solving equations. For example, rearrange Ohm’s law V=IR to highlight resistance R.

 

Solving For Variables

Recognize these equations? You will be rewriting the following given equations to solve for each variable.

1. Given that A= L x W (L times W)

i. Solve for L

ii. Solve for W

2. Given that P=2L + 2W

i. Solve for L

ii. Solve for W

3. Given that V= L x W x H

i. Solve for L

ii. Solve for

iii. Solve for H

3. Given that C =πr

i. Solve for r

4. Given that A = πr²

i. Solve for r

The following is the worksheet aligned with this task and includes the solutions.

Solving for Variables

Commentary

The purpose of this task is to provide an opportunity for students to understand that formulas and equations can be manipulated to solve for a desired variable. For example if students are asked to find the height of a rectangular prism given the length, width, and volume measurements, students should be able to use their problem solving skills to rearrange the familiar formula of V=L x W x H to = H in order to find the height of the rectangular prism.

Using formulas that are familiar to the students will allow student to gain a better understanding of how rearranging a formula is useful when having to solve for variables and can later apply this concept to more difficult equations and formulas in the future. It is also important for students to have prior knowledge of inverse operations and order of operation to successfully complete these problems.