Simplify Radicals: Math Expression Explained

by Andrew McMorgan 45 views

Hey guys! Ever stare at a math problem that looks like a foreign language? You know, the one with all the roots and variables? Well, today we're diving deep into simplifying radical expressions, specifically focusing on this beast: $7(\sqrt[3]{2 x})-3(\sqrt[3]{16 x})-3(\sqrt[3]{8 x})$. Don't worry, by the end of this, you'll be a radical-simplifying pro. We're talking about making complex expressions neat, tidy, and easy to understand. This isn't just about getting the right answer; it's about understanding the why behind the steps. So, grab your favorite study buddy (or just your favorite snack) and let's break this down, piece by piece.

Unpacking the Radical Expression

Alright, let's start by really looking at the expression we've got: $7(\sqrt[3]{2 x})-3(\sqrt[3]{16 x})-3(\sqrt[3]{8 x})$. What's the first thing you notice? We've got cube roots, right? And inside those cube roots, we have variables, xx, and different numbers. Our main goal here is to simplify this whole thing down to its simplest form. Think of it like tidying up your room – you want everything in its place, easy to access, and not a jumbled mess. In math terms, that means combining like terms. But, before we can combine terms, we need to make sure the terms are like terms. And for radicals, that means the number inside the root (the radicand) needs to be the same, and the index of the root (in this case, 3 for cube root) also needs to be the same.

Looking closely, we have 2x3\sqrt[3]{2x}, 16x3\sqrt[3]{16x}, and 8x3\sqrt[3]{8x}. See how the xx is inside each cube root? That's a good start. But the numbers 2, 16, and 8 are different. Our mission, should we choose to accept it, is to see if we can simplify 16x3\sqrt[3]{16x} and 8x3\sqrt[3]{8x} so that they might have a 2x3\sqrt[3]{2x} component. This is where our knowledge of perfect cubes comes into play. Remember perfect cubes? Like 13=11^3=1, 23=82^3=8, 33=273^3=27, 43=644^3=64, and so on. We're looking for factors within 16 and 8 that are perfect cubes.

Let's tackle 16x3\sqrt[3]{16x} first. Can we rewrite 16 as a product of a perfect cube and some other number? Yep! 16=8×216 = 8 \times 2. And since 8 is a perfect cube (23=82^3 = 8), we can rewrite 16x3\sqrt[3]{16x} as 8×2x3\sqrt[3]{8 \times 2 x}. Using the property of radicals that states abn=an×bn\sqrt[n]{ab} = \sqrt[n]{a} \times \sqrt[n]{b}, we can separate this: 83×2x3\sqrt[3]{8} \times \sqrt[3]{2x}. And since 83=2\sqrt[3]{8} = 2, this simplifies to 22x32\sqrt[3]{2x}. Pretty cool, right? We just turned a complicated-looking term into something much more manageable.

Now, let's look at 8x3\sqrt[3]{8x}. This one is even simpler! We know that 8 is a perfect cube (23=82^3 = 8). So, 8x3\sqrt[3]{8x} can be written as 83×x3\sqrt[3]{8} \times \sqrt[3]{x}. Wait, that's not quite right. It's 8×x3\sqrt[3]{8 \times x}. And 83\sqrt[3]{8} is just 2. So, 8x3\sqrt[3]{8x} simplifies to 2x32\sqrt[3]{x}. Hold on a second, guys. Let's re-evaluate. The goal is to get terms that look like 2x3\sqrt[3]{2x}. When we simplified 8x3\sqrt[3]{8x}, we got 2x32\sqrt[3]{x}. That doesn't directly match 2x3\sqrt[3]{2x}. Let's backtrack and ensure we're simplifying correctly to match the common term.

Let's re-examine 8x3\sqrt[3]{8x}. Can we factor out a perfect cube from 8? Yes, 8 itself is a perfect cube (232^3). So, 8x3=83×x3\sqrt[3]{8x} = \sqrt[3]{8} \times \sqrt[3]{x}. This gives us 2×x32 \times \sqrt[3]{x}. This simplification is correct, but it doesn't help us combine terms with 2x3\sqrt[3]{2x}. Let's re-check the initial problem and our simplification strategy. The goal is to combine terms that have the exact same radical part. So we need to see if 16x3\sqrt[3]{16x} and 8x3\sqrt[3]{8x} can be expressed in terms of 2x3\sqrt[3]{2x}.

Revisiting 16x3\sqrt[3]{16x}: We found 16x3=8×2x3=83×2x3=22x3\sqrt[3]{16x} = \sqrt[3]{8 \times 2x} = \sqrt[3]{8} \times \sqrt[3]{2x} = 2\sqrt[3]{2x}. This step is solid. Now, let's look at 8x3\sqrt[3]{8x} again. We need to see if we can manipulate it to involve 2x3\sqrt[3]{2x}. This looks a bit tricky. Is it possible there's a mistake in the original problem or our understanding? Let's assume the goal is to simplify each radical as much as possible and then combine if they become like terms. We've simplified 16x3\sqrt[3]{16x} to 22x32\sqrt[3]{2x}. What about 8x3\sqrt[3]{8x}? We know 83=2\sqrt[3]{8}=2. So 8x3=2x3\sqrt[3]{8x} = 2\sqrt[3]{x}. This term x3\sqrt[3]{x} is different from 2x3\sqrt[3]{2x}. This suggests that maybe not all terms will combine perfectly, or perhaps there's a misunderstanding of the problem's intent.

Let's reconsider the original expression: $7(\sqrt[3]{2 x})-3(\sqrt[3]{16 x})-3(\sqrt[3]{8 x})$. We correctly simplified 16x3\sqrt[3]{16x} to 22x32\sqrt[3]{2x}. Now, what about 8x3\sqrt[3]{8x}? The term inside is 8x8x. We can pull out the perfect cube 8. 8x3=83×x3=2x3\sqrt[3]{8x} = \sqrt[3]{8} \times \sqrt[3]{x} = 2\sqrt[3]{x}. This still results in a term with x3\sqrt[3]{x}, not 2x3\sqrt[3]{2x}. This implies that the term −3(8x3)-3(\sqrt[3]{8x}) might not combine with the others in the way we initially hoped. It's possible the intention was to simplify each radical term independently first.

Let's take a step back and ensure we're not missing any simplification tricks. The core idea of simplifying radicals is to extract any perfect powers from the radicand. For cube roots, we're looking for factors that are perfect cubes. For 16x3\sqrt[3]{16x}, we found 16=8×216 = 8 \times 2, where 8 is 232^3. So 16x3=8×2x3=83×2x3=22x3\sqrt[3]{16x} = \sqrt[3]{8 \times 2x} = \sqrt[3]{8} \times \sqrt[3]{2x} = 2\sqrt[3]{2x}. This part is definitely correct and gets us a 2x3\sqrt[3]{2x} term. Now for 8x3\sqrt[3]{8x}. The radicand is 8x8x. We can factor out the perfect cube 8. 8x3=83×x3=2x3\sqrt[3]{8x} = \sqrt[3]{8} \times \sqrt[3]{x} = 2\sqrt[3]{x}. This simplification is also correct. However, when we look at the original expression, we have 7(2x3)7(\sqrt[3]{2x}), −3(16x3)-3(\sqrt[3]{16x}), and −3(8x3)-3(\sqrt[3]{8x}). If we substitute our simplified forms, we get 7(2x3)−3(22x3)−3(2x3)7(\sqrt[3]{2x}) - 3(2\sqrt[3]{2x}) - 3(2\sqrt[3]{x}). This simplifies to 72x3−62x3−6x37\sqrt[3]{2x} - 6\sqrt[3]{2x} - 6\sqrt[3]{x}.

Now, we can combine the terms that have the same radical part. The terms 72x37\sqrt[3]{2x} and −62x3-6\sqrt[3]{2x} both have 2x3\sqrt[3]{2x}. Combining them gives us (7−6)2x3=12x3(7-6)\sqrt[3]{2x} = 1\sqrt[3]{2x}, or simply 2x3\sqrt[3]{2x}. The remaining term is −6x3-6\sqrt[3]{x}. So, the fully simplified expression is 2x3−6x3\sqrt[3]{2x} - 6\sqrt[3]{x}. This looks like one of our answer choices, but let's double check everything. It's crucial to be meticulous with these types of problems. Did we correctly identify all perfect cube factors? Yes. Did we apply the radical properties correctly? Yes. Did we combine like terms accurately? Yes.

Let's re-read the question and options carefully. The question asks for the simplified form of the expression. Our steps led us to 2x3−6x3\sqrt[3]{2x} - 6\sqrt[3]{x}. Now let's look at the provided options: A. −5(2x3)-5(\sqrt[3]{2 x}), B. 5(x3)5(\sqrt[3]{x}), C. 2x3−6(x3)\sqrt[3]{2 x}-6(\sqrt[3]{x}), D. Discussion category : mathematics. Option D is clearly not a mathematical expression. Option A involves only 2x3\sqrt[3]{2x} terms, which doesn't match our result because we have the −6x3-6\sqrt[3]{x} term. Option B involves only x3\sqrt[3]{x} terms, which also doesn't match. Option C, 2x3−6(x3)\sqrt[3]{2 x}-6(\sqrt[3]{x}), perfectly matches the result we derived. This confirms our step-by-step simplification process was correct.

Step-by-Step Simplification

Let's walk through the simplification process again, step by step, to ensure clarity and accuracy. We start with the given expression: $7(\sqrt[3]{2 x})-3(\sqrt[3]{16 x})-3(\sqrt[3]{8 x})$. Our primary objective is to simplify each radical term independently before attempting to combine them. This involves factoring out any perfect cubes from the radicands.

Step 1: Simplify 16x3\sqrt[3]{16x} We look for perfect cube factors within 16. We know that 16=8×216 = 8 \times 2, and 88 is a perfect cube because 23=82^3 = 8. So, we can rewrite 16x3\sqrt[3]{16x} as:

16x3=8×2x3 \sqrt[3]{16x} = \sqrt[3]{8 \times 2x}

Using the property abn=an×bn\sqrt[n]{ab} = \sqrt[n]{a} \times \sqrt[n]{b}, we get:

83×2x3 \sqrt[3]{8} \times \sqrt[3]{2x}

Since 83=2\sqrt[3]{8} = 2, this simplifies to:

22x3 2\sqrt[3]{2x}

Now, substitute this back into the original expression:

7(2x3)−3(22x3)−3(8x3) 7(\sqrt[3]{2 x})-3(2\sqrt[3]{2 x})-3(\sqrt[3]{8 x})

This becomes:

72x3−62x3−3(8x3) 7\sqrt[3]{2 x} - 6\sqrt[3]{2 x} - 3(\sqrt[3]{8 x})

Step 2: Simplify 8x3\sqrt[3]{8x} Next, we simplify the term 8x3\sqrt[3]{8x}. We look for perfect cube factors within 8. We know that 88 is itself a perfect cube (23=82^3 = 8). So, we can rewrite 8x3\sqrt[3]{8x} as:

8x3=83×x3 \sqrt[3]{8x} = \sqrt[3]{8} \times \sqrt[3]{x}

Since 83=2\sqrt[3]{8} = 2, this simplifies to:

2x3 2\sqrt[3]{x}

Now, substitute this simplified form back into our expression:

72x3−62x3−3(2x3) 7\sqrt[3]{2 x} - 6\sqrt[3]{2 x} - 3(2\sqrt[3]{x})

This results in:

72x3−62x3−6x3 7\sqrt[3]{2 x} - 6\sqrt[3]{2 x} - 6\sqrt[3]{x}

Step 3: Combine Like Terms Now we have an expression with two types of radical terms: those with 2x3\sqrt[3]{2x} and those with x3\sqrt[3]{x}. Like terms are terms that have the exact same variable part, including the radical. In this case, 72x37\sqrt[3]{2x} and −62x3-6\sqrt[3]{2x} are like terms because they both contain 2x3\sqrt[3]{2x}. We can combine their coefficients:

(7−6)2x3=12x3=2x3 (7 - 6)\sqrt[3]{2x} = 1\sqrt[3]{2x} = \sqrt[3]{2x}

The term −6x3-6\sqrt[3]{x} does not have any like terms to combine with, as it contains x3\sqrt[3]{x}.

So, the final simplified expression is the combination of these results:

2x3−6x3 \sqrt[3]{2x} - 6\sqrt[3]{x}

Conclusion: Mastering Radical Simplification

So there you have it, guys! We've successfully simplified the expression $7(\sqrt[3]2 x})-3(\sqrt[3]{16 x})-3(\sqrt[3]{8 x})$ down to its most basic form $\sqrt[3]{2x - 6\sqrt[3]{x}$. The key takeaways here are understanding how to simplify individual radical terms by factoring out perfect cubes and then combining only the terms that have identical radical parts. It's all about breaking down complex problems into manageable steps. Remember, practice makes perfect! The more you work with these types of expressions, the more intuitive the process will become.

We saw how 16x3\sqrt[3]{16x} simplifies to 22x32\sqrt[3]{2x} because 16 has a perfect cube factor of 8. We also saw that 8x3\sqrt[3]{8x} simplifies to 2x32\sqrt[3]{x} because 8 is a perfect cube. By substituting these simplified forms back into the original equation, we were able to combine the terms containing 2x3\sqrt[3]{2x} (which were 72x37\sqrt[3]{2x} and −3(22x3)=−62x3-3(2\sqrt[3]{2x}) = -6\sqrt[3]{2x}) to get 12x31\sqrt[3]{2x}. The term −3(8x3)=−3(2x3)=−6x3-3(\sqrt[3]{8x}) = -3(2\sqrt[3]{x}) = -6\sqrt[3]{x} remained separate because it contained a different radical part (x3\sqrt[3]{x}).

This detailed walkthrough should help solidify your understanding. Always look for those perfect powers within the radicand. For cube roots, these are numbers like 8, 27, 64, etc. By systematically applying the rules of exponents and radicals, you can untangle even the most intimidating-looking expressions. Keep practicing, and don't be afraid to go back and review the properties of radicals whenever you need a refresher. Mastering these skills is super valuable, not just for your math class, but for building solid problem-solving abilities overall. So go forth and simplify those radicals with confidence!