Easy Algebra Step-by-Step

Algebraic Expressions 67

expression by substituting the given numerical value for each variable and

then simplifying by performing the indicated operations, being sure to fol-

low the order of operations as you proceed.

Problem Find the value of the algebraic expression when x = 4, y = –8,

and z = –5.

a. − 5 x

b. 2 xyz

c.

6

71 x

()x^1

d.

− ()−

+

15 +

1

y+ (^5) (
z
e. xx^2 x−^12
Solution
a. − 5 x
Step 1. Substitute 4 for x in the expression − 5 x.
−^55 x=− ()
Step 2. Perform the indicated multiplication.
=−^20
Step 3. State the main result.
−^52 x=−^0 when x^ = 4.
b. 2 xyz
Step 1. Substitute 4 for x, − 8 for y, and − 5 for z
in the expression 2xyz.
22 xyz ()^4 ()^8888 ()^5
Step 2. Perform the indicated multiplication.
=^320
Step 3. State the main result.
2 xyz = 320 when x = 4, y = 8 , and z = − 5.
When you substitute negative
values into an algebraic expression,
enclose them in parentheses to
avoid careless errors.