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Combining Radical Expressions

Reference > Mathematics > Algebra > Simplifying Radicals
 

In the first section, we talked about the importance of simplifying radical expressions, and there's a reason for doing this that we didn't mention then: writing radical expressions in simplest form may allow us to combine terms and simplify an expression even more.

Take the following expression as an example:
8
+
18
+
50

This expression can be simplified by first simplifying each individual term:

8
+
18
+
50
=
4
2
+
9
2
+
25
2

2
2
+ 3
2
+ 5
2

Now, we notice that in each case we have a number multiplied by
2
, so they are essentially like terms or "like radicals," and we can combine them in the same way that we combine like terms.

2
2
+ 3
2
+ 5
2
= (2 + 3 + 5)
2
= 10
2
.

Of course, we won't always have like radicals when we simplify, but when we do, we can combine them. Here's an example: Simplify the expression
2
+
3
+
12
+
98
.

2
+
3
+
12
+
98

2
+
3
+
4
3
+
49
2
=
2
+
3
+ 2
3
+ 7
2

Note that we have two terms with
2
and two terms with
3
. These pairs of terms can be combined:

2
+
3
+ 2
3
+ 7
2

(1 + 7)
2
+ (1 + 2)
3

8
2
+ 3
3

The same process will work with variables, and it will also work with cube roots and other radicals. Simplify the following expression:
3
8x4
+
3
27x4

When we simplify each of these, we obtain:

2x
3
x
+ 3x
3
x
= 5x
3
x

Questions

1.
Simplify
10
+
40
2.
Simplify
x
+
9x
3.
Simplify
5
+
20
+
18
+
50
4.
Simplify
3
16
+
3
128
5.
Simplify
4
81x5
-
4
x5
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Cube Roots and Other RadicalsCube Roots and Other Radicals
Rationalizing the Denominator - Part OneRationalizing the Denominator - Part One
 

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