Exponent & Root: Level 2
1.
If \(3^x + 3^{x+1} = 108\), what is the value of \(x\)?
Solution (C): Factor out the smallest term, \(3^x\).
\(3^x(1 + 3^1) = 108\)
\(3^x(1 + 3) = 108\)
\(3^x(4) = 108\)
\(3^x = 108 / 4 = 27\)
Since \(27 = 3^3\), \(x = 3\).
2.
If \(8^x \times 4 = 2^{11}\), what is the value of \(x\)?
Solution (C): Convert all terms to base 2.
\(8 = 2^3\) and \(4 = 2^2\).
\((2^3)^x \times 2^2 = 2^{11}\)
\(2^{3x} \times 2^2 = 2^{11}\)
\(2^{(3x + 2)} = 2^{11}\)
Equate the exponents: \(3x + 2 = 11 \implies 3x = 9 \implies x = 3\).
3.
What is the value of \( \sqrt{72} + \sqrt{50} \)?
Solution (B): Simplify the radicals by finding perfect square factors.
1. \( \sqrt{72} = \sqrt{36 \times 2} = \sqrt{36} \times \sqrt{2} = 6\sqrt{2} \).
2. \( \sqrt{50} = \sqrt{25 \times 2} = \sqrt{25} \times \sqrt{2} = 5\sqrt{2} \).
3. Add them: \( 6\sqrt{2} + 5\sqrt{2} = 11\sqrt{2} \).
4.
What is the value of \( 27^{\frac{2}{3}} \)?
Solution (C): The denominator (3) is the root, and the numerator (2) is the power.
\( (\sqrt[3]{27})^2 \).
First, \( \sqrt[3]{27} = 3 \).
Then, \( (3)^2 = 9 \).
5.
If \(2^{2x} = 16\), what is the value of \(2^{x+1}\)?
Solution (C):
1. Solve for \(x\): \(2^{2x} = 16\). Since \(16 = 2^4\), we have \(2^{2x} = 2^4\).
2. \(2x = 4 \implies x = 2\).
3. Now find the value of \(2^{x+1}\):
\(2^{(2+1)} = 2^3 = 8\).
6.
If \(x > 0\), what is the value of \( \frac{5^{x+2} – 5^x}{5^x} \)?
Solution (C): Factor out \(5^x\) from the numerator.
\( \frac{5^x(5^2 – 1)}{5^x} \).
Cancel the \(5^x\) terms:
\( 5^2 – 1 = 25 – 1 = 24 \).
7.
If \(2^x \times 3^y = 72\), what is the value of \(x+y\)?
Solution (C): Find the prime factorization of 72.
\(72 = 8 \times 9 = 2^3 \times 3^2\).
So, \(2^x \times 3^y = 2^3 \times 3^2\).
By comparing the exponents, \(x=3\) and \(y=2\).
\(x + y = 3 + 2 = 5\).
8.
What is the value of \( \frac{\sqrt{100}}{10^{-1}} \)?
Solution (D):
1. Evaluate the numerator: \( \sqrt{100} = 10 \).
2. Evaluate the denominator: \( 10^{-1} = \frac{1}{10} \).
3. Divide: \( \frac{10}{\frac{1}{10}} = 10 \times \frac{10}{1} = 100 \).
9.
If \(4^x = 8\), what is the value of \(x\)?
Solution (C): Convert both sides to base 2.
\(4 = 2^2\) and \(8 = 2^3\).
\((2^2)^x = 2^3\)
\(2^{2x} = 2^3\)
Equate the exponents: \(2x = 3 \implies x = \frac{3}{2} = 1.5\).
10.
If \(5^x – 5^{x-1} = 100\), what is the value of \(x\)?
Solution (C): Factor out the smallest term, \(5^{x-1}\).
\(5^{x-1}(5^1 – 1) = 100\)
\(5^{x-1}(5 – 1) = 100\)
\(5^{x-1}(4) = 100\)
\(5^{x-1} = 100 / 4 = 25\)
Since \(25 = 5^2\), we have:
\(5^{x-1} = 5^2\)
\(x-1 = 2 \implies x = 3\).
Score: 0 / 10
