PRE ALGEBRA EXPRESSIONS
In algebra, xy is really 1xy, but it is written as xy-xy is really -1xy, but it is written as -xy
x and y are variables
any letter can be used as a variable
xy is the same as (x) x (y) and in a problem means to multiply
3x is the same as (3) x (x) and in a problem means to multiply
5³ is the same as 5 raised to 3, or 5 cubed, and means (5) x (5) x (5), in a problem means to multiply
Variables can be given a value
Example: x=2, y =3
You may be asked to Evaluate an Algebra problem, where a variable equals a value
Example
Evaluate this Algebra Expression:
Problem 3x + 4x when x=2
x is the variable, and 2 is the value of that variableSimply place the 2 where you find x in the expression
3(2) + 4(2) =
Then solve the problem, using order of operations, and simplify when possible
3(2) means to multiply 3 x 2 = 6
4(2) means to multiply 4 x 2 = 8
6 + 8 = 14
Answer 14
Evaluate Algebra Expressions
FYI: Negative x Negative (-) x (-) = Positive and, Positive x Negative (+) x (-) = Negative
PRACTICE Solving Algebra Expressions:
5x³ when x =-1
y³ - 2y when y =-1
6b³ when b=2
4x + 7y when x=-6 y=3
5² + 1x when x= -2
ANSWERS
5x³ when x =-1
5(-1)(-1)(-1)=
5(-1)=
-5
Answer -5
y³ - 2y when y =-1
-1³ - 2(-1) =
(-1)(-1)(-1) - (-2) =
-1 - (-2) =
- 1 + 2
1
Answer 1
6b³ when b=2
6(2)(2)(2)=
6(8)=
48
Answer 48
4x + 7y when x=-6 y=3
4(-6) + 7(3) =
-24 + 21 +
-3
Answer -3
5² + 1x when x= -2
(5)(5) + 1(-2) =
25 + -2 =
23
Answer 23
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