Algebra II : Solving and Graphing Exponential Equations

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #81 : Solving And Graphing Exponential Equations

Solve:  \(\displaystyle 2^{-2x} = (\frac{1}{2})^{6x-3}\)

Possible Answers:

\(\displaystyle \frac{3}{4}\)

\(\displaystyle \frac{4}{5}\)

\(\displaystyle \frac{3}{8}\)

\(\displaystyle \frac{3}{2}\)

\(\displaystyle \frac{3}{10}\)

Correct answer:

\(\displaystyle \frac{3}{4}\)

Explanation:

In order to solve this equation, we will need to change the base of one half to two. Use a negative exponent to rewrite this term.

\(\displaystyle \frac{1}{2}=2^{-1}\)

Rewrite the equation.

\(\displaystyle 2^{-2x} = (2^{-1})^{6x-3}\)

Since the bases are common, we can simply set the exponents equal to each other.

\(\displaystyle -2x = -(6x-3)\)

Solve for x.  Divide a negative one on both sides to eliminate the negatives.

\(\displaystyle \frac{-2x}{-1} =\frac{ -(6x-3)}{-1}\)

The equation becomes:

\(\displaystyle 2x=6x-3\)

Subtract \(\displaystyle 6x\) from both sides.

\(\displaystyle 2x-6x=6x-3-6x\)

\(\displaystyle -4x = -3\)

Divide both sides by negative four.

\(\displaystyle \frac{-4x}{-4} = \frac{-3}{-4}\)

The answer is:  \(\displaystyle \frac{3}{4}\)

Example Question #82 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 7^{x+5}=7^{12}\)

Possible Answers:

\(\displaystyle 13\)

\(\displaystyle 17\)

\(\displaystyle 8\)

\(\displaystyle 7\)

\(\displaystyle 6\)

Correct answer:

\(\displaystyle 7\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents.

\(\displaystyle 7^{x+5}=7^{12}\) With the same base, we can now write

\(\displaystyle x+5=12\) Subtract \(\displaystyle 5\) on both sides.

\(\displaystyle x=7\)

Example Question #83 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 12^{x+4}=12^{8}\)

Possible Answers:

\(\displaystyle 12\)

\(\displaystyle 6\)

\(\displaystyle 8\)

\(\displaystyle 2\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle 4\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents.

\(\displaystyle 12^{x+4}=12^{8}\) With the same base, we can now write

\(\displaystyle x+4=8\) Subtract \(\displaystyle 4\) on both sides.

\(\displaystyle x=4\)

Example Question #84 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 14^{x+16}=14^{-13}\)

Possible Answers:

\(\displaystyle 14\)

\(\displaystyle -29\)

\(\displaystyle 3\)

\(\displaystyle 19\)

\(\displaystyle -3\)

Correct answer:

\(\displaystyle -29\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents.

\(\displaystyle 14^{x+16}=14^{-13}\) With the same base, we can now write

\(\displaystyle x+16=-13\) Subtract \(\displaystyle 16\) on both sides.

\(\displaystyle x=-29\)

Example Question #85 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 12^{2x+17}=12^{-13}\)

Possible Answers:

\(\displaystyle 14\)

\(\displaystyle -15\)

\(\displaystyle -13\)

\(\displaystyle 12\)

\(\displaystyle 11\)

Correct answer:

\(\displaystyle -15\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents.

\(\displaystyle 12^{2x+17}=12^{-13}\) With the same base, we can now write

\(\displaystyle 2x+17=-13\) Subtract \(\displaystyle 17\) on both sides.

\(\displaystyle 2x=-30\) Divide \(\displaystyle 2\) on both sides.

\(\displaystyle x=-15\)

Example Question #86 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 2^{3x+8}=4\)

Possible Answers:

\(\displaystyle 3\)

\(\displaystyle -2\)

\(\displaystyle -6\)

\(\displaystyle 5\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle -2\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents. Since the bases are now different, we need to convert so we have the same base. We do know that

\(\displaystyle 4=2^2\) therefore

\(\displaystyle 2^{3x+8}=2^2\) With the same base, we can now write

\(\displaystyle 3x+8=2\) Subtract \(\displaystyle 8\) on both sides.

\(\displaystyle 3x=-6\) Divide \(\displaystyle 3\) on both sides.

\(\displaystyle x=-2\)

Example Question #86 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 3^{3x-6}=27\)

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 6\)

\(\displaystyle 2\)

\(\displaystyle 3\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle 3\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents. Since the bases are now different, we need to convert so we have the same base. We do know that

\(\displaystyle 27=3^3\) therefore

\(\displaystyle 3^{3x-6}=3^3\) With the same base, we can now write

\(\displaystyle 3x-6=3\) Add \(\displaystyle 6\) on both sides.

\(\displaystyle 3x=9\) Divide \(\displaystyle 3\) on both sides.

\(\displaystyle x=3\)

Example Question #1191 : Mathematical Relationships And Basic Graphs

Solve for \(\displaystyle x\).

\(\displaystyle 4^{2x-7}=64\)

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 9\)

\(\displaystyle 10\)

\(\displaystyle 7\)

\(\displaystyle 3\)

Correct answer:

\(\displaystyle 5\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents. Since the bases are now different, we need to convert so we have the same base. We do know that

\(\displaystyle 64=4^3\) therefore

\(\displaystyle 4^{2x-7}=4^3\) With the same base, we can now write

\(\displaystyle 2x-7=3\) Add \(\displaystyle 7\) on both sides.

\(\displaystyle 2x=10\) Divide \(\displaystyle 2\) on both sides.

\(\displaystyle x=5\)

Example Question #81 : Solving And Graphing Exponential Equations

Solve for \(\displaystyle x\).

\(\displaystyle 7^{4x+8}=1\)

Possible Answers:

\(\displaystyle -1\)

\(\displaystyle 0\)

\(\displaystyle 3\)

\(\displaystyle -2\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle -2\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents. Since the bases are now different, we need to convert so we have the same base. We do know that

\(\displaystyle 7^0=1\) therefore

\(\displaystyle 7^{4x+8}=7^0\) With the same base, we can now write

\(\displaystyle 4x+8=0\) Subtract \(\displaystyle 8\) on both sides.

\(\displaystyle 4x=-8\) Divide \(\displaystyle 4\) on both sides.

\(\displaystyle x=-2\)

Example Question #3861 : Algebra Ii

Solve for \(\displaystyle x\).

\(\displaystyle 4^{2x+5}=8^{x}\)

Possible Answers:

\(\displaystyle -5\)

\(\displaystyle 7\)

\(\displaystyle -9\)

\(\displaystyle -10\)

\(\displaystyle 12\)

Correct answer:

\(\displaystyle -10\)

Explanation:

When dealing with exponential equations, we want to make sure the bases are the same. This way we can set-up an equation with the exponents. Since the bases are now different, we need to convert so we have the same base. We do know that

\(\displaystyle 4=2^2, 8=2^3\) therefore

\(\displaystyle (2^2)^{2x+5}=(2^3)^{x}\) Apply power rule of exponents.

\(\displaystyle 2^{4x+10}=2^{3x}\) With the same base, we can now write

\(\displaystyle 4x+10=3x\) Subtract \(\displaystyle 4x\) on both sides.

\(\displaystyle 10=-x\) Divide \(\displaystyle -1\) on both sides.

\(\displaystyle -10=x\)

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