introduction to equations. expression vs. equation round 1 equation is derived from the word equate,...
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Introduction to Equations
Expression vs. EquationRound 1
• Equation is derived from the word equate, which
means one thing is the same as another thing.
• Which symbol would you associate with equate?
• An = sign!
• In Math, an equation always has an = sign.
• Notice the word equation has part of the word
equal. So when you see equation, you know
you must have an equal sign.
Equation Examples
• Notice they all have an = sign.
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Expression vs. EquationRound 2
• Expression is derived from the word
express, which means high speed or quick.
• An expression does not have an = sign.
• Notice the word expression has the word
express. This is a reminder we want to
write the expression as quickly as possible,
which means no =.
Expression Examples
• Notice no = sign.
Expression vs. EquationRound 3
• What is the relationship between an
equation and an expression?
• Such as 3x - 5 = 8
and 23a + 5b
• Notice each side of the equation is actually an
expression.
• An equation is made from 2 equal
expressions.
How to build an equation...
• Start with 2
expressions
• Put one expression on
the left side of the =
• And the other on the
right side
• Now we have an
equation.
Identify as an Equation or Expression
• An equation is like a balance. The 2 side
are always equal.
Write an equation to represent ...
Each piece of candy costs $.55. The price of p
pieces of candy is $4.40.
• What are we equating?
• The total cost to the cost of the p pieces.
• The amount charged for the candy is found
by multiplying the cost by how many
bought.
• Write the equation
• 4.40 = .55p
Write an equation to represent ...
James made a withdrawal of d dollars from his
checking account. His old balance was $980.23, and
his new balance is $526.87.
• What does withdrawal mean?
• Withdrawal indicates something being taken
away.
• What are we equating?
• Old balance minus withdrawal = New balance
• 980.23 − d = 526.87
Mya organized a pancake breakfast to raise
money to donate to the Habitat for Humanity.
She spent $35.23 on supplies and plans to
charge $4.25 for each breakfast. If P is the
profit and n is number of breakfast’s sold, what is the equation
Mya
can use to determine her profit based on the number of
breakfasts sold?
•What is being equated?
• The profit to the amount spent on supplies and amount
charged.
•How do you show spent mathematically?
• Spent indicates subtraction.
•Write the equation
• P = 4.25n − 35.23
Aiden’s parent’s deposited $1250 into a savings account for
him when he was born and contributed $325 each year, y.
Write the equation that represents the total amount, T.
•What is being equated?
• The amounts put into the account and the total amount.
•What operation does deposited and contributed indicate?
• Addition
•Write the equation
• T = 1250 + 325y
You try...
You try...Tyler receives $15 a week for school lunch, and
the cafeteria charges $2.35 for a lunch. If Tyler
purchases a lunch daily, write an equation to
determine the amount of money left, A, after d
days.
• What are we equating?
• Amount left = money received minus amount
spent on lunch
• A = 15 − 2.35d
• An equation has an = sign, an expression
does not.
• When writing equations, determine what
2 things are being equated.
• Look for key words to determine the
operation to use.
Key Points to Remember