Section 8.7 Radicals of Mixed Index
Knowing that a radical has the same properties as exponents (written as a ratio) allows us to manipulate radicals in new ways. One thing we are allowed to do is reduce, not just the radicand, but the index as well. This is shown in the following example.
Example 8.7.1.
What we have done is reduced our index by dividing the index and all the exponents by the same number (\(2\) in the previous example). If we notice a common factor in the index and all the exponnets on every factor we can reduce by dividing by that common factor. This is shown in the next example.
Example 8.7.2.
We can use the same process when there are coefficients in the problem. We will first write the coefficient as an exponential expression so we can divide the exponet by the common factor as well.
Example 8.7.3.
We can use a very similar idea to also multiply radicals where the index does not match. First we will consider an example using rational exponents, then identify the pattern we can use.
Example 8.7.4.
To combine the radicals we need a common index (just like the common denominator). We will get a common index by multiplying each index and exponent by an integer that will allow us to build up to that desired index. This process is shown in the next example.
Example 8.7.5.
Often after combining radicals of mixed index we will need to simplify the resulting radical.
Example 8.7.6.
Just as with reducing the index, we will rewrite coefficients as exponential expressions. This will aslo allow us to use exponent properties to simplify.
Example 8.7.7.
If there is a binomial in the radical then we need to keep that binomial together through the entire problem.
Example 8.7.8.
World View Note: Originally the radical was just a check mark with the rest of the radical expression in parenthesis. In \(1637\) Rene Descartes was the first to put a line over the entire radical expression
The same process is used for dividing mixed index as with multiplying mixed index. The only difference is our final answer cannot have a radical over the denominator.
Example 8.7.9.
Exercises Exercises - Radicals of Mixed Index
Exercise Group.
Reduce the following radicals.
1.
\(\sqrt[8]{16x^4y^6} \)
2.
\(\sqrt[4]{9x^2y^6} \)
3.
\(\sqrt[12]{64x^4y^6z^8} \)
4.
\(\sqrt[4]{\frac{25x^3}{16x^5}} \)
5.
\(\sqrt[6]{\frac{16x^2}{9y^4}} \)
6.
\(\sqrt[15]{x^9y^{12}z^6} \)
7.
\(\sqrt[12]{x^6y^9} \)
8.
\(\sqrt[10]{64x^8y^4} \)
9.
\(\sqrt[8]{x^6y^4z^2} \)
10.
\(\sqrt[4]{25y^2} \)
11.
\(\sqrt[9]{8x^3y^6} \)
12.
\(\sqrt[16]{81x^8y^{12}} \)
Exercise Group.
Combine the following radicals.
13.
\(\sqrt[3]{5}\sqrt{6} \)
14.
\(\sqrt[3]{7}\sqrt[4]{5} \)
15.
\(\sqrt{x}\sqrt[3]{7y} \)
16.
\(\sqrt[3]{y}\sqrt[5]{3z} \)
17.
\(\sqrt{x}\sqrt[3]{x-2} \)
18.
\(\sqrt[4]{3x}\sqrt{y+4} \)
19.
\(\sqrt[5]{x^2y}\sqrt{xy} \)
20.
\(\sqrt{ab}\sqrt[5]{2a^2b^2} \)
21.
\(\sqrt[4]{xy^2}\sqrt[3]{x^2y} \)
22.
\(\sqrt[5]{a^2b^3}\sqrt[4]{a^2b} \)
23.
\(\sqrt[4]{a^2bc^2}\sqrt[5]{a^2b^3c} \)
24.
\(\sqrt[6]{x^2yz^3}\sqrt[5]{x^2yz^2} \)
25.
\(\sqrt{a}\sqrt[4]{a^3} \)
26.
\(\sqrt[3]{x^2}\sqrt[6]{x^5} \)
27.
\(\sqrt[5]{b^2}\sqrt{b^3} \)
28.
\(\sqrt[4]{a^3}\sqrt[3]{a^2} \)
29.
\(\sqrt{xy^3}\sqrt[3]{x^2y} \)
30.
\(\sqrt[5]{a^3b}\sqrt{ab} \)
31.
\(\sqrt[4]{9ab^3}\sqrt{3a^4b} \)
32.
\(\sqrt{2x^3y^3}\sqrt[3]{4xy^2} \)
33.
\(\sqrt[3]{3xy^2z}\sqrt[4]{9x^3yz^2} \)
34.
\(\sqrt{a^4b^3c^4}\sqrt[3]{ab^2c} \)
35.
\(\sqrt{27a^5(b+1)}\sqrt[3]{81a(b+1)^4} \)
36.
\(\sqrt{8x(y+z)^5}\sqrt[3]{4x^2(y+z)^2} \)
37.
\(\frac{\sqrt[3]{a^2}}{\sqrt[4]{a}} \)
38.
\(\frac{\sqrt[3]{x^2}}{\sqrt[5]{x}} \)
39.
\(\frac{\sqrt[4]{x^2y^3}}{\sqrt[3]{xy}} \)
40.
\(\frac{\sqrt[5]{a^4b^2}}{\sqrt[3]{ab^2}} \)
41.
\(\frac{\sqrt{ab^3c}}{\sqrt[5]{a^2b^3c^{-1}}} \)
42.
\(\frac{\sqrt[5]{x^3y^4z^9}}{\sqrt[3]{xy^{-2}z}} \)
43.
\(\frac{\sqrt[4]{(3x-1)^3}}{\sqrt[5]{(3x-1)^3}} \)
44.
\(\frac{\sqrt[3]{(2+5x)^2}}{\sqrt[4]{(2+5x)}} \)
45.
\(\frac{\sqrt[3]{(2x+1)^2}}{\sqrt[5]{(2x+1)^2}} \)
46.
\(\frac{\sqrt[4]{(5-3x)^3}}{\sqrt[3]{(5-3x)^2}} \)