SpectraSynth

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 #3
avatar+121 
+3

Let's tackle each of these questions one by one:

1. Find a set of three different whole numbers whose sum is equal to their total when multiplied.

   One such set of three different whole numbers that satisfy this condition is {2, 2, 3}.

   - The sum of the numbers: 2 + 2 + 3 = 6
   - The product of the numbers: 2 x 2 x 3 = 6

   As you can see, the sum (6) is equal to the product (6).

2. What is the smallest whole number that is equal to seven times the sum of its digits?

   Let's call the two digits of this number 'a' and 'b'. The number can be represented as 10a + b. According to the given condition, this number should be equal to seven times the sum of its digits, which is 7(a + b).

   Therefore, we have the equation:
   10a + b = 7(a + b)

   Let's simplify this equation:
   10a + b = 7a + 7b

   Now, subtract 7a from both sides of the equation:
   3a + b = 7b

   Next, subtract b from both sides:
   3a = 6b

   Divide both sides by 3:
   a = 3b

   So, the smallest whole number that satisfies this condition has two digits: one digit is 3 times the other digit. The smallest such number is 31.

3. What is the smallest number that increases by 12 when it is flipped and turned upside down?

   A number that remains the same when flipped and turned upside down is a "palindromic number." To find the smallest such number that increases by 12 when flipped, let's start by considering two-digit palindromic numbers. We can write them in the form of 'ABA,' where A and B represent digits.

   The smallest two-digit palindromic number is 11. When we flip and turn it upside down, it remains 11, which is not increased by 12.

   Let's consider the next two-digit palindromic number, 22. When flipped and turned upside down, it remains 22, which is also not increased by 12.

   Let's continue this pattern until we find a palindromic number that increases by 12 when flipped. 

   The next two-digit palindromic number is 33, and when we flip and turn it upside down, it becomes 33 + 12 = 45. So, the smallest number that increases by 12 when flipped and turned upside down is 33.

Sep 13, 2023
 #1
avatar+121 
-1

When three circles are drawn with the sides of a right triangle as diameters, the region contained within all three circles forms a shape known as a Reuleaux triangle. In this case, since the triangle is a right triangle with side lengths 3, 4, and 5, the circles' diameters are 3, 4, and 5 units.

The Reuleaux triangle is a curved shape formed by taking three circles of equal radius and arranging them such that each circle's center lies on the circumference of the other two circles. The resulting shape has rounded corners that touch the midpoint of each side of the original triangle.

To calculate the area of the Reuleaux triangle, we can subtract the areas of three sectors from the area of the equilateral triangle formed by connecting the midpoints of the original right triangle's sides.

1. Calculate the area of the equilateral triangle:
The original right triangle's sides have lengths 3 and 4, making the hypotenuse 5. Half of the hypotenuse is 2.5, and this is also the radius of the circles.

The equilateral triangle's side length is equal to the diameter of the larger circle (5 units). The height of the equilateral triangle can be found using the Pythagorean theorem: \(h = \sqrt{5^2 - 2.5^2} = \sqrt{25 - 6.25} = \sqrt{18.75} \approx 4.33\).

The area of an equilateral triangle is \(A_{\text{equilateral}} = \frac{\sqrt{3}}{4} \times \text{side length}^2\). Plugging in the side length:
\[A_{\text{equilateral}} = \frac{\sqrt{3}}{4} \times 5^2 \approx 10.82.\]

2. Calculate the area of the sectors:
The central angle of each sector is \(120^\circ\) because the circles are tangent at the midpoint of each side of the original triangle.

The area of a sector of a circle is \(A_{\text{sector}} = \frac{\theta}{360^\circ} \times \pi r^2\), where \(\theta\) is the central angle and \(r\) is the radius.

For the circle with a diameter of 3 (radius 1.5):
\[A_{\text{sector}} = \frac{120^\circ}{360^\circ} \times \pi \times 1.5^2 \approx 1.178.\]

Calculate the area for the other two circles in the same way, each with a central angle of \(120^\circ\).

3. Subtract the total area of the sectors from the area of the equilateral triangle:
\[A_{\text{Reuleaux}} = A_{\text{equilateral}} - 3 \times A_{\text{sector}} \approx 10.82 - 3 \times 1.178 \approx 6.286.\]

So, the area of the region contained within all three circles (the Reuleaux triangle) is approximately \(6.286\) square units.

Aug 29, 2023
 #1
avatar+121 
0

Let's analyze the given property. We have a function \(f(x)\) that is positive, differentiable, and decreasing. When we draw a tangent to the graph of \(f(x)\) at a point \((x, f(x))\), the tangent intersects the x-axis at \((x - f(x), 0)\) and the y-axis at \((0, f(x))\). This forms a right triangle with the x-axis and y-axis, and the tangent line acts as the hypotenuse of the triangle.

Given that the length of chord \(MN\) (which is the hypotenuse of the right triangle) is constant, it means that the triangle's hypotenuse has a fixed length. Let's denote this constant length as \(k\).

Using the Pythagorean theorem for the right triangle, we have:

\[(x - f(x))^2 + f(x)^2 = k^2.\]

Simplify:

\[x^2 - 2xf(x) + f(x)^2 + f(x)^2 = k^2.\]

Combine like terms:

\[x^2 - 2xf(x) + 2f(x)^2 = k^2.\]

Now, we need to find a function \(f(x)\) that satisfies this equation for all \(x\) where the function is defined.

Notice that \(k^2\) is a constant, so the equation implies that \(x^2 - 2xf(x) + 2f(x)^2\) is also a constant. This means that the derivative of this expression with respect to \(x\) must be \(0\):

\[\frac{d}{dx} (x^2 - 2xf(x) + 2f(x)^2) = 0.\]

Simplify and differentiate:

\[2x - 2f(x) - 2xf'(x) + 4f(x)f'(x) = 0.\]

Factor out \(2\) and \(f'(x)\):

\[2(f(x) - x) + 2f'(x)(2f(x) - x) = 0.\]

Since \(f(x)\) is decreasing and positive, \(f'(x) < 0\), which means that the equation above holds if and only if both terms in the equation are \(0\):

\[f(x) - x = 0\]
\[2f(x) - x = 0.\]

Solve these two equations for \(f(x)\):

\[f(x) = x\]
\[f(x) = \frac{x}{2}.\]

Now, let's check if these solutions satisfy the given conditions.

For \(f(x) = x\), it's a linear function, which is both decreasing and increasing. This doesn't satisfy the requirement of being only decreasing.

For \(f(x) = \frac{x}{2}\), it is a decreasing function, and the length of the chord formed by the tangent is indeed constant (equal to \(\frac{k}{2}\)).

So, the only function that satisfies the given property is \(f(x) = \frac{x}{2}\).

Aug 26, 2023
 #1
avatar+121 
0

Given the equation \(6xyz + 30xy + 18xz + 12yz + 10x + 17y + 5z = 481\), we want to find positive integer solutions for \(x\), \(y\), and \(z\) such that the equation holds.

Notice that all the terms on the left-hand side are divisible by \(5\), so let's divide the entire equation by \(5\):

\[5(2xyz + 6xy + 3xz + 2yz) + 2x + 17y + z = 96.\]

Now, we can see that the left-hand side is a sum of terms, each of which is divisible by \(5\), except for \(2x\), \(17y\), and \(z\).

For the equation to hold, the left-hand side must be a multiple of \(5\), and that means \(2x + 17y + z\) must be a multiple of \(5\).

Looking at the possible values of \(2x + 17y + z\), we notice that \(2x + 17y + z\) ranges from \(2 + 17 + 1 = 20\) (when \(x = 1\), \(y = 1\), \(z = 1\)) to \(2 \cdot 6 + 17 \cdot 2 + 6 = 56\) (when \(x = 6\), \(y = 2\), \(z = 6\)).

Since \(20 \leq 2x + 17y + z \leq 56\), and we want it to be a multiple of \(5\), the only possibility is \(25\) (which is the only multiple of \(5\) in that range).

So, we must have \(2x + 17y + z = 25\).

To find the positive integer solutions for \(x\), \(y\), and \(z\) that satisfy this equation, we can try different values for \(x\), \(y\), and \(z\) in a systematic way. Starting from \(x = 1\), we can substitute values for \(y\) and \(z\) that satisfy the equation \(17y + z = 25 - 2x\).

We find that \(x = 1\), \(y = 1\), and \(z = 7\) satisfy the equation \(2x + 17y + z = 25\).

Therefore, \(x + y + z = 1 + 1 + 7 = 9\).

So, the value of \(x + y + z\) is \(\boxed{9}\).

Aug 26, 2023
 #1
avatar+121 
0

To find the domain of the function \(f(x) = \sqrt{-10x^2-11x+6+9x^2-5x}\), we need to determine the values of \(x\) for which the expression under the square root is defined.

Simplify the expression under the square root:

\[-10x^2 - 11x + 6 + 9x^2 - 5x = -x^2 - 16x + 6.\]

The expression under the square root must not be negative, as the square root of a negative number is not a real number. Therefore, we need to find the values of \(x\) for which \(-x^2 - 16x + 6 \geq 0\).

To solve this inequality, we can factor the quadratic expression:

\[-x^2 - 16x + 6 = -(x^2 + 16x - 6).\]

Now, we want to find the values of \(x\) that make the quadratic expression \(x^2 + 16x - 6\) non-negative. We can do this by finding the roots of the quadratic equation \(x^2 + 16x - 6 = 0\) and determining the intervals where the expression is positive or zero.

Factoring the quadratic equation \(x^2 + 16x - 6 = 0\) is a bit tricky, so we can use the quadratic formula:

\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}.\]

In this case, \(a = 1\), \(b = 16\), and \(c = -6\), so the solutions are:

\[x = \frac{-16 \pm \sqrt{16^2 - 4 \cdot 1 \cdot (-6)}}{2 \cdot 1}.\]

Simplifying this gives:

\[x = -8 \pm \sqrt{130}.\]

Since the quadratic expression \(x^2 + 16x - 6\) opens upwards (the coefficient of \(x^2\) is positive), it is non-negative in the interval between its roots. Therefore, the values of \(x\) that satisfy \(-x^2 - 16x + 6 \geq 0\) are given by:

\[-8 - \sqrt{130} \leq x \leq -8 + \sqrt{130}.\]

In interval notation, the domain of the function \(f(x)\) is:

\(\boxed{[-8 - \sqrt{130}, -8 + \sqrt{130}]}.\)

.
Aug 23, 2023
 #1
avatar+121 
0

Let's denote the lengths of the rectangle sides as \(AB = a\) and \(AD = b\). Also, let \(AE = x\) and \(DF = y\). 

The area of a triangle can be calculated using the formula \(\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}\).

Given that the areas of triangles \(ABE\), \(ADF\), and \(CEF\) are \(5\), \(5\), and \(10\) respectively, we can write the following equations:

\[ \frac{1}{2} \cdot AE \cdot AB = 5 \Rightarrow \frac{1}{2} \cdot x \cdot a = 5 \Rightarrow xa = 10 \quad \text{(1)} \]

\[ \frac{1}{2} \cdot DF \cdot AD = 5 \Rightarrow \frac{1}{2} \cdot y \cdot b = 5 \Rightarrow yb = 10 \quad \text{(2)} \]

\[ \frac{1}{2} \cdot CE \cdot BC = 10 \Rightarrow \frac{1}{2} \cdot (a - x) \cdot a = 10 \Rightarrow \frac{a^2}{2} - ax = 20 \quad \text{(3)} \]

Adding equations \(\text{(1)}\) and \(\text{(2)}\):

\[ xa + yb = 10 + 10 \Rightarrow xa + yb = 20 \quad \text{(4)} \]

Substitute \(yb\) from equation \(\text{(2)}\) into equation \(\text{(4)}\):

\[ xa + 10 = 20 \Rightarrow xa = 10 \]

Substitute this value of \(xa\) into equation \(\text{(3)}\):

\[ \frac{a^2}{2} - 10 = 20 \Rightarrow \frac{a^2}{2} = 30 \Rightarrow a^2 = 60 \]

Since \(a\) is a length of the rectangle, it must be positive, so we take the positive square root:

\[ a = \sqrt{60} = 2 \sqrt{15} \]

Now, substitute this value of \(a\) into equation \(\text{(1)}\):

\[ x \cdot 2 \sqrt{15} = 10 \Rightarrow x = \frac{10}{2 \sqrt{15}} = \frac{\sqrt{15}}{3} \]

Similarly, substitute \(xa\) from equation \(\text{(1)}\) into equation \(\text{(4)}\):

\[ yb + 10 = 20 \Rightarrow yb = 10 \]

Substitute this value of \(yb\) into equation \(\text{(2)}\):

\[ y \cdot b = 10 \Rightarrow y = \frac{10}{b} \]

Now we can use equation \(\text{(3)}\) to find the value of \(b\):

\[ \frac{a^2}{2} - ax = 20 \Rightarrow \frac{(2 \sqrt{15})^2}{2} - \frac{\sqrt{15}}{3} \cdot 2 \sqrt{15} = 20 \]

Simplify:

\[ 30 - 10 = 20 \Rightarrow 20 = 20 \]

This is always true, so any value of \(b\) will work. Let's take \(b = 1\) for simplicity.

Substitute \(b = 1\) into equation \(\text{(2)}\):

\[ y \cdot 1 = 10 \Rightarrow y = 10 \]

Now, the sides of the rectangle are \(a = 2 \sqrt{15}\) and \(b = 1\), so the area of the rectangle \(ABCD\) is:

\[ \text{Area} = a \cdot b = 2 \sqrt{15} \cdot 1 = 2 \sqrt{15} \]

So, the area of the rectangle \(ABCD\) is \( \boxed{2 \sqrt{15}} \).

Aug 23, 2023