TheXSquaredFactor

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UsernameTheXSquaredFactor
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Questions 3
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 #1
avatar+2442 
+1

Let's think about this problem; I've been begged to attempt to solve this problem, so I guess I will give it a shot:

 

\(\frac{x}{4000-x}=a^2\)

 

This represents the problem exactly.

 

Let's solve for x:

 

\(\frac{x}{4000-x}=a^2\) Multiply by 4000-x on both sides of the equation.
\(x=a^2(4000-x)\) Distribute the a^2 to both terms inside of the parentheses.
\(x=4000a^2-a^2x\) Add a^2*x to both sides of the equation.
\(x+a^2x=4000a^2\) Let's factor out an x from both of the terms on the left hand side of the equation.
\(x(1+a^2)=4000a^2\) Divide by 1+a^2 on both sides of the equation.
\(x=\frac{4000a^2}{1+a^2}\)  
   

 

Ok, now let's try and think about this problem logically. \(a^2\) will never be divisible by \(1+a^2\) because adding one to a number means that the numbers are co-prime. Because of this, we do not have to consider any of the cases. The only time there will be integer solutions for is when 4000 is divisible by \(1+a^2\); in other words, we need to know the factors of 4000. 

 

The factors of 4000, in order, are \({1,2,4,5,8,10,16,20,25,32,40,50,80,100,125,160,200,250,400,500,800,1000,2000,4000}\). Now, we must set the denominator to all these values and solve:

 

First is 1. Here we go:

 

\(1+a^2=1\) Subtract 1 on both sides of the equation
\(a^2=0\) Take the square root of both sides
\(|a|=0\) Split your answers into plus or minus.
\(a=0\)  
   

 

Here's a question, though. Is 0 a perfect square? Unfortunately, I am unsure about whether or not it is indeed a perfect square because definitions vary. Many people agree with the definition of if \(\sqrt{a}\in\mathbb{Z}\)where \({a}\in\mathbb{Z}\) , then that number is a perfect square. With that definition, 0 is a perfect square. However, some define it as \(\sqrt{a}\in\mathbb{N}\) where \({a}\in\mathbb{Z}\). In this case, 0 would be excluded. It's an open question, really, without a concrete answer. If you know whether or not an answer exists to this question, I would appreciate feedback. Anyway, let's try the next factor, 2:

 

You know what? There is a method to make this go even faster, anyway! Let's take the following set and subtract 1 from every term.

 

Now,\({1,2,4,5,8,10,16,20,25,32,40,50,80,100,125,160,200,250,400,500,800,1000,2000,4000}\)

transforms into \({0,1,3,4,7,9,15,19,24,31,39,49,79,99,124,159,199,249,399,499,799,999,1999,3999}\). Now, out of those, which ones are perfects squares? They are the following:

 

\(0,1,4,9,49\)

 

Now, take the square roots of the numbers in the set:

 

\(0,1,2,3,7\)

 

Therefore, the sum of the positive perfect square integers is \(0+1+2+3+7=13\).

 #2
avatar+2442 
+1

This is a rare example in mathematics where, I believe, parentheses is necessary in order to evaluate the expression without ambiguity. I will demonstrate why.

 

Strictly speaking, asinus's interpretation is incorrect. If you were to evaluate this with a calculator inputted like as is, the calculator would evaluate it as \(\frac{6^2}{2}*3+4\). This is because the 2(3) is really multiplication, so division takes precedence since it is comes first in the expression. First it does 6^2, then it divides 6^2 by 2 because division is first from left to right, and then it multiplies that quantity by 3. Here is another example with a variable 

 

8/2y

 

Using the same logic as above, this equation, in fraction form is strictly \(\frac{8}{2}y\)--not \(\frac{8}{2y}\). Some would argue, however, that 2y is a term, so it shouldn't be separated.  

 

How do we eliminate this ambiguity if there is no fraction button to speak of? Use parentheses! 

 

Asinus's interpretation of \(\frac{6^2}{2*3}+4\) will be unambiguous once you add 1 set of parentheses with \(6^2/(2(3))+4\). Now, the only correct interpretation is \(\frac{6^2}{2*3}+4\) because the parentheses indicate that we are dividing by the quantity of the product of 2 and 3.

 

The strict interpretation is \(\frac{6^2}{2}*3+4\) should be written like \((6^2/2)(3)+4\). In this case, the quantity of six squared divided by two is all multiplied by three. No more ambiguity.

 

Okay, after all of this ranting, now I will evaluate what I believe to be, under the current rules of the order of operations, the way to evaluate the expression 6^2/2(3)+4 as \(\frac{6^2}{2}*3+4\):

 

\(\frac{6^2}{2}*3+4\) Evaluate the numerator. \(6^2=36\)
\(\frac{36}{2}*3+4\) Simplify the fraction by recognizing that the 36 is divisible by 2 because 36 is even.
\(18*3+4\) Do multiplication before addition.
\(54+4\)  
\(58\)  
   

 

 

 

                    
 

 #1
avatar+2442 
+1

There are many ways to prove that a triangle is right, but this method, I believe, is the best and most efficient. Our first task is to find the actual length of the sides. To do this, I will utilize a fomula called the distance formula. The formula is the following:

 

\(d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)

 

Let's use this to find the distances:

 

\(d_{\overline{AB}}=\sqrt{(-3-4)^2+(5-7)^2}\)\(d_{\overline{BC}}=\sqrt{(4-(-1))^2+(7-(-2))^2}\)\(d_{\overline{CA}}=\sqrt{(-1-(-3))^2+(-2-5)^2}\)
\(d_{\overline{AB}}=\sqrt{(-7)^2+(-2)^2}\)\(d_{\overline{BC}}=\sqrt{5^2+9^2}\)\(d_{\overline{CA}}=\sqrt{2^2+(-7)^2}\)
\(d_{\overline{AB}}=\sqrt{49+4}=\sqrt{53}\)\(d_{\overline{BC}}=\sqrt{25+81}=\sqrt{106}\)\(d_{\overline{CA}}=\sqrt{4+49}=\sqrt{53}\)
   

 

Do you remember that famous formula called the Pythagorean theorem? It describes the relationship of the sides of a right triangle, stating that the sum of the squares of the legs is equal to the hypotenuse squared:

 

\(a^2+b^2=c^2\)

 

The converse happens to also be true; in other words, if \(a^2+b^2=c^2\), then the triangle is right. Let's check to see if this condition is true.

 

Before we do, however, we need to understand which sides are the legs and which is the hypotenuse. The hypotenuse is always the longest side of the triangle. Although we do not know the exact length of the segments AB, BC, and CA, we can determine which side is the longest since we know that \(AB=\sqrt{53}\)\(BC=\sqrt{106}\), and \(CA=\sqrt{53}\). Logically speaking,  \(\sqrt{106}>\sqrt{53}\) because the higher the radicand, the larger the actual value is. Now that we understand the hypotenuse is \(BC\), the legs do not matter. One is assigned the value and one is assigned the value b. To confirm that this triangle is indeed right, plug in the values into the equation:
 

\(a^2+b^2=c^2\)This is the Pythangorean theorem. Plug in the side lengths of the legs for a and b and the hypotenuse for c
\(\sqrt{53}^2+\sqrt{53}^2=\sqrt{106}^2\)Check to see if this condition is true. If it is, it validates that the triangle is indeed right. Of course, squaring a nonnegative number inside of a radical negates the radical.
\(53+53=106\) 
\(106=106\)This statement is true; 106=106. 
  

 

Because \(a^2+b^2=c^2\), we can conclude that this triangle is indeed right.

 #1
avatar+2442 
0

Wow! That is such a mouthful of an expression, but I will attempt to evaluate it anyway. 

 

If I am not mistaken, the expression is the following:
 

\((\frac{62^{62}-62^{62-1}}{62^{62-1}})^{\sqrt{62^{62-1}+62^{62}-62^{62-2}}}\)

 

\((\frac{62^{62}-62^{62-1}}{62^{62-1}})^{\sqrt{62^{62-1}+62^{62}-62^{62-2}}}\) I'll start with the fraction portion of this expression
\(\frac{62^{62}-62^{62-1}}{62^{62-1}}\) First, I will break the fraction up with the following fraction rule that states \(\frac{a\pm b}{c}=\frac{a}{c}\pm\frac{b}{c}\).
\(\frac{62^{62}-62^{62-1}}{62^{62-1}}=\frac{62^{62}}{62^{62-1}}-\frac{62^{62-1}}{62^{62-1}}\) Of course, \(\frac{62^{62-1}}{62^{62-1}}=1 \) because any nonzero number divided by itself is always one.
\(\frac{62^{62}}{62^{62-1}}-\frac{62^{62-1}}{62^{62-1}}=\frac{{62^{62}}}{62^{61}}-1\) We will utilize an exponent rule that states that \(\frac{a^b}{a^c}=a^{b-c}\).
\(\frac{{62^{62}}}{62^{61}}=62^{62-61}=62^1=62\) Reinsert this in for \(\frac{{62^{62}}}{62^{61}}\).
\(62-1=61\) Ok, we have successfully simplified from \(\frac{62^{62}-62^{62-1}}{62^{62-1}}\) to 61. Reinsert 61 for \(\frac{62^{62}-62^{62-1}}{62^{62-1}}\) in the original expression.
\(61^{\sqrt{62^{62-1}+62^{62}-62^{62-2}}}\) I will convert \(62^{62-1}\) into a fraction by using the converse of a fraction rule I utilized before. It is \(a^{b-c}=\frac{a^b}{a^c}\)
\({\sqrt{62^{62-1}+62^{62}-62^{62-2}}}={\sqrt{\frac{62^{62}}{62^1}+62^{62}-62^{62-2}}}\) Multiply \(62^{62}\) by \(\frac{62}{62}\) to create a common denominator.
\(\frac{62^{62}}{1}*\frac{62}{62}=\frac{62*62^{62}}{62^1}\) Insert this back into the equation, too.
\({\sqrt{\frac{62^{62}}{62^1}+62^{62}-62^{62-2}}}={\sqrt{\frac{62^{62}}{62^1}+\frac{62*62^{62}}{62^1}-62^{62-2}}}\) Add \(\frac{62^{62}}{62^1}+\frac{62*62^{62}}{62^1}\) together. 
\({\sqrt{\frac{62^{62}}{62^1}+\frac{62*62^{62}}{62^1}-62^{62-2}}}=\sqrt{\frac{63*62^{62}}{62^1}-62^{60}}\) Convert \(\frac{62^{60}}{1}*\frac{62}{62}\) into a fraction over 62 by doing
\(\frac{62^{60}}{1}*\frac{62}{62}=\frac{62^{60}*62}{62}=\frac{62^{61}}{62}\) Replace   \(62^{60}\) with \(\frac{62^{61}}{62}\)
\(\sqrt{\frac{63*62^{62}}{62^1}-62^{60}}=\sqrt{\frac{63*62^{62}}{62^1}-\frac{62^{61}}{62}}\) Subtract the fractions.
\(\sqrt{\frac{63*62^{62}}{62^1}-\frac{62^{61}}{62}}=\sqrt{\frac{63*62^{62}-62^{61}}{62}}\) "Distribute" the square root to both the numerator and denominator.
\(\sqrt{\frac{63*62^{62}-62^{61}}{62}}=\frac{\sqrt{63*62^{62}-62^{61}}}{\sqrt{62}}\) Rationalize the denominator by multiplying \(\frac{\sqrt{63*62^{62}-62^{61}}}{\sqrt{62}}\) by \(\frac{\sqrt{62}}{\sqrt{62}}\).
\(\frac{\sqrt{63*62^{62}-62^{61}}}{\sqrt{62}}*\frac{\sqrt{62}}{\sqrt{62}}\) Use the square root rule that states that \(\sqrt{x}*\sqrt{y}=\sqrt{xy}\)
\(\frac{\sqrt{62(63*62^{62}-62^{61})}}{62}\) Distribute the 62 to all terms. 
\(\frac{\sqrt{62(63*62^{62}-62^{61})}}{62}=\frac{\sqrt{62*63*62^{62}-62*62^{61}}}{62}\) Simplify.
\(\frac{\sqrt{3906*62^{62}-62^{62}}}{62}\) Do the subtraction in the numerator.
\(3906*62^{62}-62^{62}=3905*62^{62}\) Reinsert that back into the expression. I will simplify \(\sqrt{3905*62^{62}}\) by using the rule that \(\sqrt{ab}=\sqrt{a}*\sqrt{b}\)
\(\sqrt{3905}*\sqrt{62^{62}}\)  
\(\sqrt{62^{62}}=\sqrt{62^{31}*62^{31}}=62^{31} \) Plug this back into the original expression
\(\frac{62^{31}\sqrt{3905}}{62}=62^{30}*\sqrt{3905}\) Factor out the common factor of 62
   


At this point, I cannot simplify the exponent any further. I have done an impressive job of simplifying 

\((\frac{62^{62}-62^{62-1}}{62^{62-1}})^{\sqrt{62^{62-1}+62^{62}-62^{62-2}}}\) into \(61^{({62^{30}*\sqrt{3905}})}\). I will now have to utilize an extremely accurate calculator for a calculation of this size. My only option is to provide you with an exponent tower; that's how huge it is!

 

\((\frac{62^{62}-62^{62-1}}{62^{62-1}})^{\sqrt{62^{62-1}+62^{62}-62^{62-2}}}=61^{({62^{30}\sqrt{3905}})}\approx 10^{10^{55.81927966668297}}\)

.