Problem

Simplify the Radical Expression fourth root of 8a^3b* fourth root of 10a^2b^7

The problem requests a simplification of two radical expressions, each involving a fourth root. The first expression is the fourth root of $8a^3b$, and the second is the fourth root of $10a^2b^7$. The task is to multiply these two radical expressions together and then simplify the result, which may involve combining like terms under the radical, reducing exponents according to the properties of radicals and exponents, and simplifying any numerical coefficients. The goal is to express the product in the simplest radical form possible.

$\sqrt[4]{8 a^{3} b} \cdot \sqrt[4]{10 a^{2} b^{7}}$

Answer

Expert–verified

Solution:

Step:1

Express $10 a^{2} b^{7}$ as $b^{4} \cdot (10 a^{2} b^{3})$.

Step:1.1

Extract $b^{4}$ from the expression: $\sqrt[4]{8 a^{3} b} \cdot \sqrt[4]{10 a^{2} (b^{4} b^{3})}$

Step:1.2

Rearrange to place $a^{2}$ at the front: $\sqrt[4]{8 a^{3} b} \cdot \sqrt[4]{10 b^{4} a^{2} b^{3}}$

Step:1.3

Switch the positions of $10$ and $b^{4}$: $\sqrt[4]{8 a^{3} b} \cdot \sqrt[4]{b^{4} \cdot 10 a^{2} b^{3}}$

Step:1.4

Enclose in brackets: $\sqrt[4]{8 a^{3} b} \cdot \sqrt[4]{b^{4} \cdot 10 (a^{2} b^{3})}$

Step:1.5

Enclose in brackets again for clarity: $\sqrt[4]{8 a^{3} b} \cdot \sqrt[4]{b^{4} \cdot (10 a^{2} b^{3})}$

Step:2

Extract terms from under the radical sign: $\sqrt[4]{8 a^{3} b} \cdot (|b| \sqrt[4]{10 a^{2} b^{3}})$

Step:3

Combine the two radicals: $\sqrt[4]{8 a^{3} b} (|b| \sqrt[4]{10 a^{2} b^{3}})$.

Step:3.1

Apply the product rule for radicals: $\sqrt[4]{10 a^{2} b^{3} (8 a^{3} b)} |b|$

Step:3.2

Multiply $8$ by $10$: $\sqrt[4]{80 a^{2} b^{3} (a^{3} b)} |b|$

Step:3.3

Combine the exponents using the power rule $a^{m} a^{n} = a^{m + n}$: $\sqrt[4]{80 a^{5} b^{3} b} |b|$

Step:3.4

Sum the exponents $3$ and $2$: $\sqrt[4]{80 a^{5} b^{3} b} |b|$

Step:3.5

Raise $b$ to the power of $1$: $\sqrt[4]{80 a^{5} (b^{1} b^{3})} |b|$

Step:3.6

Combine the exponents: $\sqrt[4]{80 a^{5} b^{4}} |b|$

Step:3.7

Sum the exponents $1$ and $3$: $\sqrt[4]{80 a^{5} b^{4}} |b|$

Step:4

Rewrite $80 a^{5} b^{4}$ as $(2 a b)^{4} \cdot (5 a)$.

Step:4.1

Factor $16$ from $80$: $\sqrt[4]{16 (5) a^{5} b^{4}} |b|$

Step:4.2

Represent $16$ as $2^{4}$: $\sqrt[4]{2^{4} \cdot 5 a^{5} b^{4}} |b|$

Step:4.3

Factor out $a^{4}$: $\sqrt[4]{2^{4} \cdot 5 (a^{4} a) b^{4}} |b|$

Step:4.4

Rearrange $a$: $\sqrt[4]{2^{4} \cdot 5 (a^{4}) b^{4} a} |b|$

Step:4.5

Rearrange $5$: $\sqrt[4]{(2^{4} (a^{4})) b^{4} \cdot 5 a} |b|$

Step:4.6

Express $(2^{4} (a^{4})) b^{4}$ as $(2 a b)^{4}$: $\sqrt[4]{(2 a b)^{4} \cdot 5 a} |b|$

Step:4.7

Enclose in brackets: $\sqrt[4]{((2 a b)^{4} \cdot (5 a))} |b|$

Step:5

Extract terms from under the radical: $|2 a b| \sqrt[4]{5 a} |b|$

Step:6

Eliminate non-negative terms from the absolute value: $2 |a b| \sqrt[4]{5 a} |b|$

Step:7

Multiply the terms: $2 |a b| \sqrt[4]{5 a} |b|$.

Step:7.1

To multiply absolute values, multiply the terms inside: $2 |b (a b)| \sqrt[4]{5 a}$

Step:7.2

Raise $b$ to the power of $1$: $2 |a (b^{1} b)| \sqrt[4]{5 a}$

Step:7.3

Raise $b$ to the power of $1$ again: $2 |a (b^{1} b^{1})| \sqrt[4]{5 a}$

Step:7.4

Combine the exponents: $2 |a b^{2}| \sqrt[4]{5 a}$

Step:7.5

Add the exponents $1$ and $1$: $2 |a b^{2}| \sqrt[4]{5 a}$

Step:8

Eliminate non-negative terms from the absolute value: $2 b^{2} |a| \sqrt[4]{5 a}$

Knowledge Notes:

  1. Radical Expressions: Expressions that contain roots, such as square roots or fourth roots.

  2. Product Rule for Radicals: $\sqrt[n]{a} \cdot \sqrt[n]{b} = \sqrt[n]{a \cdot b}$, which allows us to multiply two radicals with the same index.

  3. Power Rule for Exponents: $a^{m} \cdot a^{n} = a^{m + n}$, which is used to combine like bases with exponents.

  4. Absolute Value: The absolute value of a number is its distance from zero on the number line, denoted by $|a|$. For non-negative terms, the absolute value is the term itself.

  5. Simplifying Radical Expressions: The process involves factoring out perfect powers, combining like terms under the radical, and then simplifying the expression inside and outside the radical.

  6. Factoring: The process of breaking down an expression into its constituent factors, which can be useful when simplifying expressions, especially under a radical.

  7. Exponent Laws: These laws are used to manipulate expressions with exponents during the simplification process.

  8. Rewriting Expressions: Often, expressions can be rewritten in a form that makes it easier to simplify or factor, such as expressing a number as a power of another number.

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