Mathematics Grade 11 15 min

Solve exponential equations using factoring

Solve exponential equations using factoring

Tutorial Preview

1

Introduction & Learning Objectives

Learning Objectives Recognize exponential equations that can be expressed in a factorable form. Rewrite exponential equations into a quadratic form, such as a(b^x)^2 + c(b^x) + d = 0. Use substitution to transform a complex exponential equation into a simpler polynomial equation. Apply factoring techniques, including Greatest Common Factor (GCF) and trinomial factoring, to solve the transformed equation. Solve for the original variable by back-substituting and solving the resulting basic exponential equations. Verify solutions and identify extraneous roots that may arise during the solving process. Ever seen an equation like `4^x - 2^x - 6 = 0` and thought it was impossible? 🤔 What if it's just a familiar quadratic equation in disguise? This tutorial will teach you a...
2

Key Concepts & Vocabulary

TermDefinitionExample Exponential EquationAn equation in which the variable appears in the exponent of an expression.`5^(2x) - 5^x = 20` is an exponential equation because the variable `x` is in the exponent. Quadratic FormAn equation that can be written as `au^2 + bu + c = 0`, where `u` is an expression involving a variable. For our topic, `u` will be an exponential term like `b^x`.The equation `(3^x)^2 - 6(3^x) + 9 = 0` is in quadratic form, where `u = 3^x`. Substitution (u-substitution)A strategy used to simplify a complex equation by replacing a recurring expression with a single variable, typically `u`.In `4^x + 2^x - 2 = 0`, we can rewrite it as `(2^x)^2 + 2^x - 2 = 0`. By letting `u = 2^x`, the equation simplifies to `u^2 + u - 2 = 0`. Zero Product PropertyA property stating that i...
3

Core Formulas

Power of a Power Rule (b^m)^n = b^{mn} This rule is essential for identifying the quadratic structure. For example, you can rewrite `9^x` as `(3^2)^x`, which simplifies to `3^{2x}` or, more usefully, `(3^x)^2`. Product of Powers Rule b^m \cdot b^n = b^{m+n} Use this rule to break apart exponents before factoring. For example, `2^{x+1}` can be rewritten as `2^x \cdot 2^1`, which helps in identifying a common factor of `2^x`. Zero Product Property If A \cdot B = 0, then A = 0 or B = 0 This is the fundamental principle of solving by factoring. Once you have factored the equation into parts, you set each part equal to zero and solve independently.

4 more steps in this tutorial

Sign up free to access the complete tutorial with worked examples and practice.

Sign Up Free to Continue

Sample Practice Questions

Easy
Which of the following equations is expressed in a factorable quadratic form, `au^2 + bu + c = 0`, where `u` is an exponential term?
A.5^(x+2) - 5^x = 120
B.(3^x)^2 - 6(3^x) + 9 = 0
C.2x^2 - 3x + 1 = 0
D.7^x = 49
Easy
To solve the equation `25^x - 6(5^x) + 5 = 0` using the u-substitution method described in the tutorial, what is the most appropriate choice for `u`?
A.u = x
B.u = 25^x
C.u = 5^x
D.u = 5
Easy
According to the Power of a Power Rule, how can `9^x` be rewritten to reveal the quadratic structure in an equation like `9^x - 4(3^x) + 3 = 0`?
A.3^(2x)
B.(3^x)^2
C.3 * 3^x
D.9 * x

Want to practice and check your answers?

Sign up to access all questions with instant feedback, explanations, and progress tracking.

Start Practicing Free

More from Exponential and logarithmic functions

Ready to find your learning gaps?

Take a free diagnostic test and get a personalized learning plan in minutes.