Answer:
To evaluate a variable expression means to find the value of the expression when the variable is (or variables are) replaced by a number (or numbers).
Here is a variable expression:
3
x
+
7
.
To evaluate this expression when
x
=
2
mean to substitute
2
in place of
x
, and find the number (the value). [see note below]
3
(
2
)
+
7
=
6
+
7
=
13
.
When
x
=
2
, the expression has a value of `
13
.
If we evaluate the same expression when
x
=
10
, we get:
3
(
10
)
+
7
=
30
+
7
=
37
.
Here's a variable expression with two variables :
3
x
−
2
y
In order to evaluate this expression, we'll need values (numbers) for both
x
and
y
.
Evaluate the expression
3
x
−
2
y
when
x
=
4
and
y
=
5
3
(
4
)
−
2
(
5
)
=
12
−
10
=
2
If we change the values to
x
=
5
and
y
=
4
, we get
3
(
5
)
−
2
(
4
)
=
15
−
8
=
7
.
Step-by-step explanation:
