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Question
name:
pre-calculus 11: chapter 5 quiz – calculator
date:
- simplify radicals and collect like terms. state any restrictions on the values for the variables.
a. $4\sqrt{45x^3} - \sqrt{27x} + 17\sqrt{3x} - 9\sqrt{125x^3}$
$x\geq0$
- expand and simplify. state any restrictions on the values for the variables.
a. $(10r - 4\sqrt3{4r})(2\sqrt3{6r^2} + 3\sqrt3{12r})$
$r\geq0$
- simplify.
a. $\frac{6\sqrt3{4v^7}}{\sqrt3{14v}}, v > 0$
r^2} \)).
Step 4: State restrictions
For cube roots, \( r \) can be any real number (cube roots are defined for all real numbers).
Step 1: Rewrite radicals as exponents (optional, but helpful)
\( \sqrt[6]{49v^7} = (49v^7)^{\frac{1}{6}} = 49^{\frac{1}{6}}v^{\frac{7}{6}} \).
\( \sqrt[3]{14v} = (14v)^{\frac{1}{3}} = 14^{\frac{1}{3}}v^{\frac{1}{3}} \).
Step 2: Rewrite with common denominator for exponents
\( v^{\frac{7}{6}} \div v^{\frac{1}{3}} = v^{\frac{7}{6} - \frac{2}{6}} = v^{\frac{5}{6}} \).
Rewrite \( 49^{\frac{1}{6}} \) as \( (7^2)^{\frac{1}{6}} = 7^{\frac{1}{3}} \).
Rewrite \( 14^{\frac{1}{3}} = (2 \cdot 7)^{\frac{1}{3}} = 2^{\frac{1}{3}} \cdot 7^{\frac{1}{3}} \).
Step 3: Simplify the coefficient
\( \frac{7^{\frac{1}{3}}}{2^{\frac{1}{3}} \cdot 7^{\frac{1}{3}}} = \frac{1}{2^{\frac{1}{3}}} \) (the \( 7^{\frac{1}{3}} \) terms cancel).
Step 4: Combine back
Now we have \( \frac{1}{2^{\frac{1}{3}}} \cdot v^{\frac{5}{6}} \). To rationalize or simplify, rewrite \( \frac{1}{2^{\frac{1}{3}}} = 2^{-\frac{1}{3}} \), but alternatively, rewrite the original expression using radicals:
Original expression: \( \frac{\sqrt[6]{49v^7}}{\sqrt[3]{14v}} = \frac{\sqrt[6]{49v^7}}{\sqrt[6]{(14v)^2}} \) (since \( \sqrt[3]{x} = \sqrt[6]{x^2} \)).
Simplify inside the sixth root: \( \frac{49v^7}{(14v)^2} = \frac{49v^7}{196v^2} = \frac{v^5}{4} \).
Thus, \( \sqrt[6]{\frac{v^5}{4}} = \frac{\sqrt[6]{v^5}}{\sqrt[6]{4}} = \frac{v^{\frac{5}{6}}}{4^{\frac{1}{6}}} \).
Rationalize \( 4^{\frac{1}{6}} = (2^2)^{\frac{1}{6}} = 2^{\frac{1}{3}} \), so multiply numerator and denominator by \( 2^{\frac{2}{3}} \):
\( \frac{v^{\frac{5}{6}} \cdot 2^{\frac{2}{3}}}{2^{\frac{1}{3}} \cdot 2^{\frac{2}{3}}} = \frac{v^{\frac{5}{6}} \cdot 2^{\frac{2}{3}}}{2} \).
But a simpler approach: Rewrite \( \sqrt[6]{49v^7} = \sqrt[6]{49v^6 \cdot v} = v\sqrt[6]{49v} \), and \( \sqrt[3]{14v} = \sqrt[6]{(14v)^2} = \sqrt[6]{196v^2} \).
Then \( \frac{v\sqrt[6]{49v}}{\sqrt[6]{196v^2}} = v \cdot \sqrt[6]{\frac{49v}{196v^2}} = v \cdot \sqrt[6]{\frac{1}{4v}} \).
Wait, earlier steps had an error. Let’s correct:
\( \sqrt[6]{49v^7} = \sqrt[6]{49v^6 \cdot v} = v\sqrt[6]{49v} \) (since \( v > 0 \), \( \sqrt[6]{v^6} = v \)).
\( \sqrt[3]{14v} = \sqrt[6]{(14v)^2} = \sqrt[6]{196v^2} \).
Thus, \( \frac{v\sqrt[6]{49v}}{\sqrt[6]{196v^2}} = v \cdot \sqrt[6]{\frac{49v}{196v^2}} = v \cdot \sqrt[6]{\frac{1}{4v}} = v \cdot \frac{1}{\sqrt[6]{4v}} \).
Rationalize the denominator: Multiply numerator and denominator by \( \sqrt[6]{(4v)^5} \):
\( v \cdot \frac{\sqrt[6]{(4v)^5}}{\sqrt[6]{(4v)^6}} = v \cdot \frac{\sqrt[6]{1024v^5}}{4v} = \frac{\sqrt[6]{1024v^5}}{4} \).
Simplify \( 1024 = 2^{10} \), so \( \sqrt[6]{2^{10}v^5} = 2^{\frac{10}{6}}v^{\frac{5}{6}} = 2^{\frac{5}{3}}v^{\frac{5}{6}} \).
Thus, \( \frac{2^{\frac{5}{3}}v^{\frac{5}{6}}}{4} = \frac{2^{\frac{5}{3}}v^{\frac{5}{6}}}{2^2} = 2^{\frac{5}{3} - 2}v^{\frac{5}{6}} = 2^{-\frac{1}{3}}v^{\frac{5}{6}} \).
Alternatively, rewrite \( 2^{-\frac{1}{3}} = \frac{1}{\sqrt[3]{2}} \), so \( \frac{v^{\frac{5}{6}}}{\sqrt[3]{2}} \). Multiply numerator and denominator by \( \sqrt[3]{4} \) to rationalize:
\( \frac{v^{\frac{5}{6}} \cdot \sqrt[3]{4}}{\sqrt[3]{2} \cdot \sqrt[3]{4}} = \frac{v^{\frac{5}{6}} \cdot \sqrt[3]{4}}{\sqrt[3]{8}} = \frac{v^{\frac{5}{6}} \cdot \sqrt[3]{4}}{2} \).
But the simplest form (after correcting earlier errors) is:
Starting over:
\( \frac{\sqrt[6]{49v^7}}{\sqrt[3]{14v}} = \frac{(49v^7)^{\frac{1}{6}}}{(14v)^{\frac{1}{3}}} = \frac{49^{\frac{1}{6}}v^{\frac{7}{6}}}{14^{\frac{1}{3}}v^{\frac{1}{3}}} = \frac{7^{\frac{2}{6}}v^{\frac{7}{6}}}{(2 \cdot 7)^{\frac{1}{3}}v^{\frac{2}{6}}} = \frac{7^{\frac{1}{3}}v^{\frac{7}{6}}}{2^{\frac{1}{3}} \cdot 7^{\frac{1}{3}}v^{\fr…
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Expanded and simplified: \( 20r\sqrt[3]{6r^2} + 30r\sqrt[3]{12r} - 16r\sqrt[3]{3} - 24\sqrt[3]{6r^2} \); Restriction: \( r \in \mathbb{R} \) (all real numbers)