Variables and Equations Pre-Algebra
Learning Objective I can solve equations with variables.
Vocabulary Equation A mathematical sentence formed by placing an equal sign between two expressions. Example: x - 8 = 12 Solution A number that produces a true statement when substituted for the variable in an equation. Example: 2 + x = 5; x=3 is a solution
Example 1 - Writing Verbal Sentences as Equations 1. The sum of x and 6 is 9. Equation: x + 6 = 9 2. The difference of 12 and y is 15. Equation: 12 - y = The product of -4 and p is 32. Equation: -4p = The quotient of n and 2 is 9. Equation: n/2 = 9
Example 2: Checking Possible Solutions Tell whether 9 or 7 is a solution of x - 5=2. 1) Substitute 9 for x x - 5 = = 2 ? 4 2 9 is not a solution
Example 2: Checking Possible Solutions Tell whether 9 or 7 is a solution of x - 5=2. 1) Substitute 7 for x. x - 5 = = 2 ? 2 = 2 7 is a solution
Skill Check Write the verbal sentence as an equation. 1. The sum of 3 and z is z = The quotient of m and 6 is 4. m/6 = 6 Tell whether -5 or 5 is a solution of -8y= is a solution
Example 3 - Solving Equations Using Mental Math Equation: x + 3 = 11 Question: What number plus 3 equals 11? Solution: 8 Check: = 11 Equation: 16 - m = 9 Question: 16 minus what number equals 9? Solution: 7 Check: = 9
Example 3 - Solving Equations Using Mental Math Equation: 20 = 5t Question: 20 equals 5 times what number? Solution: 4 Check: 20 = 5(4) Equation: y/6 = -3 Question: What number divided by 6 equals -3? Solution: -18 Check: -18/6 = -3
Skill Check Solve the equations using mental math. 1. x - 10 = 7 x = n = -6 x = w = -15 x = = 36/x x = 9
Skill Check Go-cart rides cost $5 each at a county fair. During the first day of the fair, the go-cart operator takes in a total of $1000. How many times did people ride the go-carts that day? Write and solve an equation to find the answer. 5x = 1000, x = 200; 200 times
Classwork Assignment Page #s 8-15, even, 32-34