SAT · Math · Equivalent Expressions

Exponents, Radicals, and Rational Exponents

10 min readPreviewBy Uzair Khan

What you'll be able to do

Exponent rules (product, quotient, power, zero and negative exponents), converting between rational exponents and radicals, and simplifying radical expressions.

Introduction

Exponent and radical manipulation appears throughout the Advanced Math domain, which makes up roughly 35% of your SAT Math score. Every time the test gives you an expression and asks "which of the following is equivalent to…," it is probing your ability to fluently apply exponent laws and convert between radical and rational-exponent forms. These skills also underpin polynomial work, factoring, and rational expressions — the sibling subtopics covered in their own notes (Polynomial Operations, Factoring Polynomials, Rational Expressions).


Core Concept

The central idea is that exponents, radicals, and rational exponents are three notations for the same underlying idea: repeated multiplication and its inverse. Switching fluently among them — without a calculator — is what the SAT tests.

The Two-Way Bridge: Rational Exponents ↔ Radicals

xm/n=xmn=(xn)mx^{m/n} = \sqrt[n]{x^m} = \left(\sqrt[n]{x}\right)^m

The denominator of the rational exponent is the index (root), and the numerator is the power. For example:

82/3=823=643=48^{2/3} = \sqrt[3]{8^2} = \sqrt[3]{64} = 4

You can also compute it the other way: (83)2=22=4\left(\sqrt[3]{8}\right)^2 = 2^2 = 4 — same answer. Choose whichever order keeps the numbers smaller.

Simplifying Radical Expressions

Factor the radicand to pull out perfect powers:

72=36⋅2=62\sqrt{72} = \sqrt{36 \cdot 2} = 6\sqrt{2}

To combine radical terms, first simplify each one, then collect like-radical terms exactly as you would collect like terms in algebra.

28+18=2⋅22+32=42+32=722\sqrt{8} + \sqrt{18} = 2 \cdot 2\sqrt{2} + 3\sqrt{2} = 4\sqrt{2} + 3\sqrt{2} = 7\sqrt{2}

Unlock the full Equivalent Expressions note with Nova

You're reading the preview. Unlock the complete note — every worked example, examiner pitfall and practice question — plus 24/7 AI tutoring from Nova that teaches directly from these notes.

Keep learning

Explore SAT Math tutoring →

View the full Math syllabus →

Part of Novark's free SAT Math notes