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  1. Home
  2. 12th grade
  3. Algebra II
  4. Exercise : Solve equations of the form x^a=b

Solve equations of the form x^a=b Algebra II

Find the solution(s) of the following equations.

x^4=21

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even.
  • x= \sqrt[a]{b} if a is odd.

The problem x^4=21 is solved by taking the 4^{th} root of 21:

x^4=21

x=\pm \sqrt[4]{21}

The solutions are x=\pm \sqrt[4]{21}

x^2=16

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even
  • x= \sqrt[a]{b} if a is odd

The problem x^2=16 is solved by taking the square root of 16:

x^2=16

x=\pm 4

The solutions are x=\pm 4.

x^3=27

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even
  • x= \sqrt[a]{b} if a is odd

The problem x^3=27 is solved by taking the cube root of 27:

x^3=27

x= \sqrt[3]{27}

x=3

The solution is x=3.

x^9=15

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even
  • x= \sqrt[a]{b} if a is odd

The problem x^9=15 is solved by taking the 9^{th} root of both sides:

x^9=15

x= \sqrt[9]{15}

The solution is x= \sqrt[9]{15}.

x^7=512

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even
  • x= \sqrt[a]{b} if a is odd

The problem x^7=512 is solved by taking the 7^{th} root of 512:

x^7=512

x= \sqrt[7]{512}

The solution is x= \sqrt[7]{512}.

x^6=99

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even
  • x= \sqrt[a]{b} if a is odd

The problem x^6=99 is solved by taking the 6^{th} root of 99:

x^6=99

x=\pm \sqrt[6]{99}

The solutions are x=\pm \sqrt[6]{99}.

x^7+15=200

Subtracting 15 from both sides gives:

x^7+15-15=200-15

x^7=185

Solving x^a=b requires taking the a^{th} root of b:

  • x=\pm \sqrt[a]{b} if a is even
  • x= \sqrt[a]{b} if a is odd

The problem x^7=185 is solved by taking the 7^{th} root of 185:

x^7=185

x= \sqrt[7]{185}

The solution is x= \sqrt[7]{185}.

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See also
  • Course : Exponential and logarithmic equations and inequalities
  • Exercise : Convert from logarithmic form to exponential form
  • Exercise : Solve equations of the form a^x=b
  • Exercise : Solve inequalities of the form a^x > or < b
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