Page 7 - Algebra 1

Finding the Value of an Expression
The value of an algebraic expression depends upon the value of the variables.
For example, the area of a square is a2, where ‘a’ is the side of the square. When ‘a’ is 4 cm, the area is
22 16cm andwhen‘a’is9cm,theareais81cm .
Worked Example 4
Find the value of the expression for x = 3.
a.4x2 –1 b.3x2 –2x+1
Solution:
a.4x2 –1
Put the value of x = 3
4 (3)2 – 1
= 4(9) – 1 = 35
b.3x2 –2x+1
Put the value of x = 3
3(3)2 – 2(3) + 1
= 3(9) – 6 + 1 = 27 – 6 + 1 = 22
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ALGEBRA