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Prep 2 SS · Mathematics
Numbers · Real numbers

Operations with Radicals

Before you start, make sure you know: Special products (Secondary Year 2)
Before you start, make sure you know: Extracting factors (Secondary Year 3)

An architect in Querétaro designs a triangular skylight and finds that its height is $\sqrt{18}+\sqrt{6}$ meters. How does she calculate the exact area without approximating with a calculator? For that you need to operate with radicals: add them, multiply them, and remove them from denominators. By the end of this page you will answer that question.

Like radicals: adding and subtracting

Step-by-step calculation of adding and subtracting like radicals after extracting factors: 3 square root of 50 plus 2 square root of 18 minus square root of 8 equals 19 square root of 2. 3√50 + 2√18 − √8 = 3·5√2 + 2·3√2 − 2√2 = 15√2 + 6√2 − 2√2 = 19√2
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Simplify the following mathematical expression by extracting factors from the radicals and grouping like terms: $5\sqrt{12} - \sqrt{27} + 2\sqrt{75}$

Simplify the following mathematical expression by extracting factors from the radicals and grouping like terms:

$5\sqrt{12} - \sqrt{27} + 2\sqrt{75}$

Solve
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Extract all possible factors from the following radicals and simplify the resulting expression to obtain a single term: $3\sqrt{80} - 2\sqrt{45} + \sqrt{20}$

Extract all possible factors from the following radicals and simplify the resulting expression to obtain a single term:

$3\sqrt{80} - 2\sqrt{45} + \sqrt{20}$

Solve

Extracting and introducing factors

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Extract all possible factors from the following radicals to obtain the simplest expression: a) $\sqrt{72x^4y^3}$ b) $\sqrt[3]{128a^5}$

Extract all possible factors from the following radicals to obtain the simplest expression:

  1. a) $\sqrt{72x^4y^3}$
  1. b) $\sqrt[3]{128a^5}$
Solve
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Insert the factors inside the radical in the following expressions: a) $3 \sqrt{5x}$ b) $2a^2 \sqrt[3]{3a}$

Insert the factors inside the radical in the following expressions:

  1. a) $3 \sqrt{5x}$
  1. b) $2a^2 \sqrt[3]{3a}$
Solve
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Find the height ($h$) of a triangular solar panel if we know that its area is $\sqrt{24}$ square meters and its base measures $\sqrt{2}$ meters. Remember that the area…

Find the height ($h$) of a triangular solar panel if we know that its area is $\sqrt{24}$ square meters and its base measures $\sqrt{2}$ meters. Remember that the area of a triangle is calculated as $A = \frac{\text{base} \times \text{altura}}{2}$. Express the result simplifying the radicals.

h A = √24 m² base = √2 m
Solve

Multiplying and dividing radicals

Multiplication of radicals with different indices written as powers of base 2 with a fractional exponent. ∛4 · √2 = 2^(2/3) · 2^(1/2) everything as powers of 2 = 2^(7/6) add the exponents: 2/3 + 1/2 = 7/6 = ⁶√2⁷ = 2·⁶√2 a 2 comes out of the root
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Perform the following operations with radicals of the same index and express the result in the simplest possible form: a) $\sqrt[4]{2} \times \sqrt[4]{8}$ b)…

Perform the following operations with radicals of the same index and express the result in the simplest possible form:

  1. a) $\sqrt[4]{2} \times \sqrt[4]{8}$
  1. b) $\frac{\sqrt[3]{81}}{\sqrt[3]{3}}$
Solve
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In the design of a new smartphone chip, one of the connections has a length given by the product of two radical components. Calculate the exact value of this length by…

In the design of a new smartphone chip, one of the connections has a length given by the product of two radical components. Calculate the exact value of this length by simplifying the following product and expressing it under a single radical:

$\sqrt[3]{a^2} \times \sqrt[4]{a^3}$

Solve
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In a graphic design studio, work is being done on a logo that uses a spiral based on rectangles. One of the critical segments has a length $L$ defined by the operation…

In a graphic design studio, work is being done on a logo that uses a spiral based on rectangles. One of the critical segments has a length $L$ defined by the operation between the following radicals with different indices. Calculate its exact value and simplify it:

$$L = \frac{\sqrt[4]{32} \times \sqrt[3]{16}}{\sqrt[6]{2}}$$ L
Solve

The root of a root

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Apply the properties of radicals to reduce to a single root and simplify the final result: $\sqrt[3]{\sqrt{64x^{12}}}$

Apply the properties of radicals to reduce to a single root and simplify the final result:

$\sqrt[3]{\sqrt{64x^{12}}}$

Solve
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Reduce the following expression to a single radical as simple as possible, applying the properties of a root of a root and the extraction of factors:…

Reduce the following expression to a single radical as simple as possible, applying the properties of a root of a root and the extraction of factors:

$\sqrt{\sqrt[3]{64x^8}}$

Solve
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Simplify the following expression with nested radicals to convert it into a power with a fractional exponent with base $a$: $$\sqrt[3]{a^2 \times \sqrt{a \times…

Simplify the following expression with nested radicals to convert it into a power with a fractional exponent with base $a$:

$$\sqrt[3]{a^2 \times \sqrt{a \times \sqrt[4]{a^3}}}$$
Solve

Products with binomials

To multiply expressions with radicals, use the distributive property and the special products, just as with polynomials.

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A technology company is designing a new smartphone model. The screen is rectangular and its exact dimensions are given by the following radicals: the base measures…

A technology company is designing a new smartphone model. The screen is rectangular and its exact dimensions are given by the following radicals: the base measures $\sqrt{12}$ cm and the height measures $\sqrt{3}$ cm. Calculate the area of the screen, expressing the result in simplified form.

√12 cm √3 cm Area = ? √12 × √3
Solve
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Perform the following combined operation with radicals, applying the distributive property and simplifying like terms: $(\sqrt{3} + 2) \times (2\sqrt{3} - 5)$

Perform the following combined operation with radicals, applying the distributive property and simplifying like terms:

$(\sqrt{3} + 2) \times (2\sqrt{3} - 5)$

Solve
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Calculate the area of a square plaza whose side measures $(2 + \sqrt{5})$ meters. Express the result in exact form, simplifying any radicals that appear when expanding…

Calculate the area of a square plaza whose side measures $(2 + \sqrt{5})$ meters. Express the result in exact form, simplifying any radicals that appear when expanding the binomial.

2² 2√5 2√5 (√5)² Side = 2 + √5 2 √5 2 √5
Solve

Rationalizing a monomial denominator

Rationalization of a fraction with a square root in the denominator by multiplying the numerator and denominator by that root. 6 √3 · √3 √3 multiply the top and the bottom by √3 = 6√3 3 = 2√3 (6 ÷ 3 = 2)
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Rationalise the following fractions so that no radical remains in the denominator. Remember to simplify the final result if possible: a) $\frac{10}{\sqrt{2}}$ b)…

Rationalise the following fractions so that no radical remains in the denominator. Remember to simplify the final result if possible:

  1. a) $\frac{10}{\sqrt{2}}$
  1. b) $\frac{3}{\sqrt[3]{5}}$
Solve
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Rationalise the following expressions to eliminate the radicals from the denominator and simplify the final result: a) $\dfrac{6}{\sqrt[3]{9}}$ b) $\dfrac{10}{\sqrt{5}}$

Rationalise the following expressions to eliminate the radicals from the denominator and simplify the final result:

  1. a) $\dfrac{6}{\sqrt[3]{9}}$
  1. b) $\dfrac{10}{\sqrt{5}}$
Solve
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An interior decorator wants to place a wooden moulding around a large square mirror that has an area of $20 \text{ m}^2$. Express the perimeter of the mirror in…

An interior decorator wants to place a wooden moulding around a large square mirror that has an area of $20 \text{ m}^2$. Express the perimeter of the mirror in simplified radical form (extract factors if necessary).

Area 20 m² Perimeter = ? l = ?
Solve

Rationalizing a binomial denominator (conjugate)

Step-by-step rationalization of a fraction with a binomial denominator by multiplying the numerator and denominator by its conjugate expression. 4 √5−1 · √5+1 √5+1 conjugate: (√5−1)(√5+1) = 5−1 = 4
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An architect needs to calculate the pressure exerted by a structure on the ground. After completing the initial calculations, the resulting expression is as follows.…

An architect needs to calculate the pressure exerted by a structure on the ground. After completing the initial calculations, the resulting expression is as follows. Rationalise it using the conjugate of the denominator and simplify it as much as possible:

$\dfrac{4}{\sqrt{7} - \sqrt{3}}$

Solve
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Rationalise and simplify the following fraction. You must work out the numerator after rationalising to obtain the simplest possible expression: $$\frac{2\sqrt{6} -…

Rationalise and simplify the following fraction. You must work out the numerator after rationalising to obtain the simplest possible expression:

$$\frac{2\sqrt{6} - 3\sqrt{2}}{2\sqrt{3} + \sqrt{2}}$$
Solve

Denominator with three radicals

When the denominator has three terms, such as $\sqrt2+\sqrt3-\sqrt5$, you group two of them so that the denominator looks like a binomial $A-B$ and rationalize twice.

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Rationalise the following expression. Note that, as there are three square roots in the denominator, you may need to multiply by the conjugate more than once:…

Rationalise the following expression. Note that, as there are three square roots in the denominator, you may need to multiply by the conjugate more than once:

$$\frac{4}{\sqrt{2} + \sqrt{3} - \sqrt{5}}$$
Solve
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Rationalise the following expression and simplify the result by extracting all possible factors from the radicals: $$\frac{\sqrt{2}}{\sqrt{2} + \sqrt{3} - \sqrt{5}}$$ Is…

Rationalise the following expression and simplify the result by extracting all possible factors from the radicals:

$$\frac{\sqrt{2}}{\sqrt{2} + \sqrt{3} - \sqrt{5}}$$

Is the result a rational or irrational number? Justify your answer by analysing the structure of the number obtained.

Solve

For the last exercise: after rationalizing, you get the sum of a whole number and radicals that are not like radicals, such as $\sqrt6$ and $\sqrt{15}$. Analyze that structure to decide whether the result is rational or irrational.

Putting it all together and applications

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Simplify the following combined expression as much as possible, extracting factors from the radicals and rationalising any terms necessary to group the numerical part:…

Simplify the following combined expression as much as possible, extracting factors from the radicals and rationalising any terms necessary to group the numerical part:

$$3\sqrt{175} - \frac{5}{\sqrt{7}} + \sqrt[4]{441} - 2\sqrt{112}$$
Solve
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An architect is designing a triangular skylight for a new shopping center. The design requires the base of the skylight to be an equilateral triangle whose height is…

An architect is designing a triangular skylight for a new shopping center. The design requires the base of the skylight to be an equilateral triangle whose height is exactly $H = \sqrt{18} + \sqrt{6}$ meters. Calculate the exact value of the area of the skylight, expressing the result as a simplified radical in $m^2$.

H = √18 + √6 L L L
Solve
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A metal structure in the shape of a rectangular prism is to be built, whose dimensions (width, length and height) are given by the following expressions in meters:…

A metal structure in the shape of a rectangular prism is to be built, whose dimensions (width, length and height) are given by the following expressions in meters:

  • $a = \sqrt{2} + \sqrt{3}$

  • $b = \sqrt{2} - \sqrt{3} + \sqrt{6}$

  • $c = \sqrt{6}$

Calculate the total volume of the structure. The result must be a real number expressed in exact form (with radicals if necessary).

Solve

Summary

See all the exercises in this section