Lesson 9 of 16, 13 min read

Multiplying, dividing and simplifying radicals

The product and quotient rules for radicals, simplifying square roots and higher roots, radicals with different indices, powers of radicals and roots of roots.

In this lesson, variables under a radical stand for positive numbers.

The product and quotient rules

Simplest radical form

A square root is in simplest form when the radicand has no perfect-square factor other than \(1\). The product rule, read backwards, lets you pull those factors out.

For variables there's a quick rule: divide the exponent by the index. The quotient is the exponent outside; the remainder stays inside. For \(\sqrt{x^7}\): \(7 \div 2 = 3\) remainder \(1\), so \(x^3\sqrt{x}\).

Different indices

To multiply \(\sqrt{3}\) by \(\sqrt[3]{2}\), first rewrite both with a common index, the LCM of the indices.

Powers of radicals and roots of roots

Practice

Quick check

What is \(\sqrt{50}\) in simplest radical form?

Quick check

What is \(\sqrt{\sqrt{81}}\)?

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