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Simplifying rational exponents

Simplify:

  1. 5 ( 2 x 3 4 ) ( 3 x 1 5 )
  2. ( 16 9 ) 1 2

  1. 30 x 3 4 x 1 5 Multiply the coefficients . 30 x 3 4 + 1 5 Use properties of exponents . 30 x 19 20 Simplify .

  2. ( 9 16 ) 1 2    Use definition of negative exponents . 9 16    Rewrite as a radical . 9 16    Use the quotient rule . 3 4    Simplify .
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Simplify ( 8 x ) 1 3 ( 14 x 6 5 ) .

28 x 23 15

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Access these online resources for additional instruction and practice with radicals and rational exponents.

Key concepts

  • The principal square root of a number a is the nonnegative number that when multiplied by itself equals a . See [link] .
  • If a and b are nonnegative, the square root of the product a b is equal to the product of the square roots of a and b See [link] and [link] .
  • If a and b are nonnegative, the square root of the quotient a b is equal to the quotient of the square roots of a and b See [link] and [link] .
  • We can add and subtract radical expressions if they have the same radicand and the same index. See [link] and [link] .
  • Radical expressions written in simplest form do not contain a radical in the denominator. To eliminate the square root radical from the denominator, multiply both the numerator and the denominator by the conjugate of the denominator. See [link] and [link] .
  • The principal n th root of a is the number with the same sign as a that when raised to the n th power equals a . These roots have the same properties as square roots. See [link] .
  • Radicals can be rewritten as rational exponents and rational exponents can be rewritten as radicals. See [link] and [link] .
  • The properties of exponents apply to rational exponents. See [link] .

Section exercises

Verbal

What does it mean when a radical does not have an index? Is the expression equal to the radicand? Explain.

When there is no index, it is assumed to be 2 or the square root. The expression would only be equal to the radicand if the index were 1.

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Where would radicals come in the order of operations? Explain why.

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Every number will have two square roots. What is the principal square root?

The principal square root is the nonnegative root of the number.

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Can a radical with a negative radicand have a real square root? Why or why not?

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Numeric

For the following exercises, simplify each expression.

Algebraic

For the following exercises, simplify each expression.

8 1 3 x

2 2 + 2 6 x 1 −3 x

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w 3 2 32 w 3 2 50

w 2 w

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12 x 2 + 2 3

3 x 3 x 2

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162 x 6 16 x 4 4

3 2 x 2 4 2

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128 z 3 3 −16 z 3 3

6 z 2 3

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Real-world applications

A guy wire for a suspension bridge runs from the ground diagonally to the top of the closest pylon to make a triangle. We can use the Pythagorean Theorem to find the length of guy wire needed. The square of the distance between the wire on the ground and the pylon on the ground is 90,000 feet. The square of the height of the pylon is 160,000 feet. So the length of the guy wire can be found by evaluating 90,000 + 160,000 . What is the length of the guy wire?

500 feet

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A car accelerates at a rate of 6 4 t  m/s 2 where t is the time in seconds after the car moves from rest. Simplify the expression.

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Extensions

For the following exercises, simplify each expression.

8 16 4 2 2 1 2

−5 2 −6 7

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m n 3 a 2 c −3 a −7 n −2 m 2 c 4

m n c a 9 c m n

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x 64 y + 4 y 128 y

2 2 x + 2 4

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( 250 x 2 100 b 3 ) ( 7 b 125 x )

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64 3 + 256 4 64 + 256

3 3

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Questions & Answers

f(x)=x/x+2 given g(x)=1+2x/1-x show that gf(x)=1+2x/3
Ken Reply
proof
AUSTINE
sebd me some questions about anything ill solve for yall
Manifoldee Reply
how to solve x²=2x+8 factorization?
Kristof Reply
x=2x+8 x-2x=2x+8-2x x-2x=8 -x=8 -x/-1=8/-1 x=-8 prove: if x=-8 -8=2(-8)+8 -8=-16+8 -8=-8 (PROVEN)
Manifoldee
x=2x+8
Manifoldee
×=2x-8 minus both sides by 2x
Manifoldee
so, x-2x=2x+8-2x
Manifoldee
then cancel out 2x and -2x, cuz 2x-2x is obviously zero
Manifoldee
so it would be like this: x-2x=8
Manifoldee
then we all know that beside the variable is a number (1): (1)x-2x=8
Manifoldee
so we will going to minus that 1-2=-1
Manifoldee
so it would be -x=8
Manifoldee
so next step is to cancel out negative number beside x so we get positive x
Manifoldee
so by doing it you need to divide both side by -1 so it would be like this: (-1x/-1)=(8/-1)
Manifoldee
so -1/-1=1
Manifoldee
so x=-8
Manifoldee
SO THE ANSWER IS X=-8
Manifoldee
so we should prove it
Manifoldee
x=2x+8 x-2x=8 -x=8 x=-8 by mantu from India
mantu
lol i just saw its x²
Manifoldee
x²=2x-8 x²-2x=8 -x²=8 x²=-8 square root(x²)=square root(-8) x=sq. root(-8)
Manifoldee
I mean x²=2x+8 by factorization method
Kristof
I think x=-2 or x=4
Kristof
x= 2x+8 ×=8-2x - 2x + x = 8 - x = 8 both sides divided - 1 -×/-1 = 8/-1 × = - 8 //// from somalia
Mohamed
1KI POWER 1/3 PLEASE SOLUTIONS
Prashant Reply
hii
Amit
how are you
Dorbor
well
Biswajit
can u tell me concepts
Gaurav
Find the possible value of 8.5 using moivre's theorem
Reuben Reply
which of these functions is not uniformly cintinuous on (0, 1)? sinx
Pooja Reply
which of these functions is not uniformly continuous on 0,1
Basant Reply
solve this equation by completing the square 3x-4x-7=0
Jamiz Reply
X=7
Muustapha
=7
mantu
x=7
mantu
3x-4x-7=0 -x=7 x=-7
Kr
x=-7
mantu
9x-16x-49=0 -7x=49 -x=7 x=7
mantu
what's the formula
Modress
-x=7
Modress
new member
siame
what is trigonometry
Jean Reply
deals with circles, angles, and triangles. Usually in the form of Soh cah toa or sine, cosine, and tangent
Thomas
solve for me this equational y=2-x
Rubben Reply
what are you solving for
Alex
solve x
Rubben
you would move everything to the other side leaving x by itself. subtract 2 and divide -1.
Nikki
then I got x=-2
Rubben
it will b -y+2=x
Alex
goodness. I'm sorry. I will let Alex take the wheel.
Nikki
ouky thanks braa
Rubben
I think he drive me safe
Rubben
how to get 8 trigonometric function of tanA=0.5, given SinA=5/13? Can you help me?m
Pab Reply
More example of algebra and trigo
Stephen Reply
What is Indices
Yashim Reply
If one side only of a triangle is given is it possible to solve for the unkown two sides?
Felix Reply
cool
Rubben
kya
Khushnama
please I need help in maths
Dayo Reply
Okey tell me, what's your problem is?
Navin
Practice Key Terms 6

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Source:  OpenStax, Algebra and trigonometry. OpenStax CNX. Nov 14, 2016 Download for free at https://legacy.cnx.org/content/col11758/1.6
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