Solving Equations and Rearranging Formulas Presented by Mr. Laws Math I/JCMS Resource: Glencoe/McGraw-Hill/Algebra 1

Common Core Standard A.CED.4 – Rearrange formulas o highlight a quantity of interest, using the same reasoning as in solving equations.

Essential Question “Using mathematical reasoning, what are the necessary steps taken to solve an equation by rearranging it for a specific variable or formula?”

Solve for Variables 2x – 4y = 8 -2x -4y = 8 – 2x -4 -4 y = 8 – 2x -4 You can solve for a specific variable if the equation contains more than one variable by using the properties of equality to isolate the variable. Example 1: Solve 2x - 4y = 8 for y 2x – 4y = 8 -2x -4y = 8 – 2x -4 -4 y = 8 – 2x -4 y = 2x – 8 4 or

Solve for Variables Example 2: Solve 3m – n = km – 8 for m 3m – km = -8 + n m(3 – k) = -8 + n 3 – k 3 – k m = -8 + n 3 - k m = n - 8 3 - k Or

Solving a Formula for a Specific Variable There will be real world problems that may require you to rearrange a formula in order to solve it for a specific variable. For Example: The formula represents the circumference of a circle, or the distance around the circle, where d is the diameter. If an airplane could fly around Earth at the equator without stopping, it would have traveled about 24,900 miles. Find the diameter of Earth You must rearrange the formula to solve for d the diameter. The new formula to for the diameter

Summary/Reflection What do you now know about rearranging an equation or formula for a specific variable? Is there anything else you would want to learn? Can you answer the essential question to this lesson?