Mathematics
Grade 11
15 min
Multiply by 7
Multiply by 7
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Apply the power of a power rule to expressions by multiplying the exponent by 7.
Simplify complex expressions involving rational exponents where the base is 7 or a power of 7.
Solve equations with rational exponents that require raising a term to the 7th power.
Convert expressions between radical form (specifically the 7th root) and exponential form.
Evaluate numerical expressions with rational exponents where a key step involves multiplying an exponent by 7.
Analyze how multiplying a rational exponent by 7 transforms the value and structure of an algebraic expression.
What is the 7th power of the 7th root of a number? 🤔 This lesson reveals how this simple-sounding question unlocks a powerful shortcut in advanced algebra!
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Key Concepts & Vocabulary
TermDefinitionExample
Rational ExponentAn exponent expressed as a fraction m/n, where 'm' represents the power and 'n' represents the root. The expression b^(m/n) is equivalent to the nth root of b raised to the mth power.The expression 8^(2/3) means 'the cube root of 8, squared'. So, (∛8)² = 2² = 4.
Power of a Power RuleWhen raising a power to another power, you multiply the exponents.(x^3)^2 = x^(3*2) = x^6. In this lesson, we focus on cases like (x^(a/b))^7 = x^(7a/b).
Base of 7An expression where the base number being raised to a power is 7.7^(1/2), which is the square root of 7.
7th RootA number that must be multiplied by itself 7 times to equal a given value. It is the inverse operation of raising to the 7th power.The 7th root of 128 is 2, because 2^7 =...
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Core Formulas
Power Rule with Multiplication by 7
(b^(m/n))^7 = b^((m/n) * 7) = b^(7m/n)
Use this rule to simplify an expression where a base with a rational exponent is raised to the 7th power. You multiply the rational exponent by 7.
Solving Equations with 7th Roots
If x^(a/7) = c, then (x^(a/7))^(7/a) = c^(7/a), which simplifies to x = c^(7/a).
To solve for a variable raised to a fractional exponent with 7 in the denominator, raise both sides of the equation to the reciprocal power. This often involves multiplying the existing exponent by 7.
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Challenging
For the expression (b^(m/n))^7 to simplify to an exponent that is a positive integer, which of the following must be true, assuming m is a positive integer?
A.n must be a multiple of 7.
B.m must be a multiple of 7.
C.n must be a factor of 7m.
D.m and n must both be 7.
Challenging
If (x^(a/4))^7 = x^(21/4), and (y^(7/b))^3 = y^(21/5), what is the value of (a/b)?
A.3/5
B.5/3
C.15
D.1/15
Challenging
Solve for x in the equation: (x^(-3/7))^(-7/3) = 7.
A.1/49
B.1/7
C.-7
D.7
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