Vocabulary: An equation is
a math sentence with an equal sign (=). It
says two amounts are the same.
βCorrect! An equation always has an equal sign. It says the left
side and the right side are the same value.
βNot quite. Look for the equal sign (=). An equation says two sides
are equal. The answer is B: 3 + 5 = 8.
Warm-Up 2
Is the number sentence 4 + 7 = 12 true or false?
Hint: Add the left side first. Does 4 + 7 equal 12?
βCorrect! 4 + 7 = 11, not 12. The equation is false.
βCheck again: 4 + 7 = 11, not 12. Since the sides are not equal, the
equation is false.
P
Practice
5 questions
Practice 1
Is x = 6 a solution to the equation
x + 4 = 10?
What is a solution? A
solution is a value that makes the equation
true. Replace x with 6 and check: does the left side equal
the right side? Try it: 6 + 4 = ?
Explain how you know:
Sentence frame: "When I replace x with ___, I get ___ + 4 = ___.
Since ___ equals ___, the equation is ___."
βYes! Substituting 6: 6 + 4 = 10. Both sides equal 10, so x = 6 is a
solution.
βSubstitute 6 for x: 6 + 4 = 10 β. Both sides are equal, so x = 6
is a solution.
Practice 2
Which value of n makes the equation
n β 3 = 9 true?
Strategy: Try each answer. Replace n with
the number, then subtract 3. Which one gives you 9?
Show your substitution work:
Sentence frame: "I substituted ___ for n. ___ minus 3 equals ___.
Since ___ equals 9, the solution is n = ___."
βCorrect! 12 β 3 = 9 β. The value n = 12 makes the equation
true.
βTry substituting each value: 12 β 3 = 9 β. The answer is
C, n = 12.
Practice 3
Sort each math sentence into the correct category.
Remember: An equation has
an equal sign (=). An expression does not
have an equal sign β it is just a math phrase.
5 + x = 12
3y + 7
18 = 2 Γ 9
4a β 1
m Γ· 3 = 6
10 + 2b
Equations
Expressions
βAll correct! Equations have equal signs. Expressions are math
phrases without an equal sign.
βSome items are in the wrong group. Remember: equations have an =
sign, expressions do not. Try again!
Practice 4
Find the value that makes each equation true.
Strategy: Think about what number goes in the blank
to make both sides equal. You can use mental math or work backward.
a.+ 8 = 15
b.20 β= 15
c.3 Γ= 12
Sentence frame: "I know the answer is ___ because ___ and ___ equals
___."