Questions   
Sort: 
 #1
avatar+174 
0

Since ∠APB=∠PBA, triangles ABP and PBA are isosceles. This means that ∠ABP=∠BAP=21​(180∘−∠APB).

 

Similarly, since ∠BPC=∠PBC, triangles BPC and PBC are isosceles. This means that ∠BPC=∠PBC=21​(180∘−∠BPC).

Summing the angle measures in △ABC gives $ \angle ABC + \angle ACB + \angle BAC = 180^\circ$. Since ∠APB=∠PBA and ∠BPC=∠PBC, we can rewrite this as [ \angle ABP + \angle BAP + \angle BPC + \angle PBC + \angle BAC = 180^\circ. ] Substituting what we found for each angle measure, we get [ \frac{1}{2} (180^\circ - \angle APB) + \frac{1}{2} (180^\circ - \angle APB) + \frac{1}{2} (180^\circ - \angle BPC) + \frac{1}{2} (180^\circ - \angle BPC) + \angle BAC = 180^\circ. ] Simplifying the left side gives [ 2 \cdot 180^\circ - (\angle APB + \angle BPC) + \angle BAC = 180^\circ. ] We are given that ∠ABC−∠ACB=24∘, which is the same as ∠BAP−∠BPC=24∘ since ∠APB=∠BAP and ∠BPC=∠PBC. Substituting again, we get [ 2 \cdot 180^\circ - (\angle BAP + \angle BPC) + \angle BAC = 180^\circ \Rightarrow 2 \cdot 180^\circ - (180^\circ + 24^\circ) + \angle BAC = 180^\circ. ] Solving for ∠BAC gives ∠BAC=36∘.

Since the angles in a triangle sum to 180∘, we can find ∠PBC as follows: [ \angle PBC = 180^\circ - \angle BPC - \angle BAC = 180^\circ - \frac{1}{2} (180^\circ - \angle BPC) - 36^\circ. ] Substituting ∠BAP−∠BPC=24∘ again, we get [ \angle PBC = 180^\circ - \frac{1}{2} (180^\circ - (\angle BAP + 24^\circ)) - 36^\circ = 180^\circ - 90^\circ - 12^\circ = \boxed{78^\circ}. ]

Apr 16, 2024
 #1
avatar+174 
0

We can solve this problem by considering different cases for how the siblings are arranged across the two rows.

Case 1: Splitting Each Pair

In this case, we have one child from each pair in each row. There are 3!=6 ways to arrange the children in each row (since sibling order within a row doesn't matter). However, we've overcounted since we haven't considered which sibling from each pair sits in which row. So, for each arrangement, we need to multiply by 23 to account for the two choices (sibling 1 or sibling 2) for each of the three pairs. This gives us 6⋅23=48 arrangements for this case.

Case 2: Keeping Pairs Together

Here, both siblings from one or two pairs sit in the same row. There are two sub-cases to consider:

Two Pairs Together: There are (23​)=3 ways to choose which two pairs will sit together (the third pair will be split). Once chosen, there are 2!=2 ways to arrange the two siblings within each pair that sits together, and again 2 ways to decide which row the combined pair sits in. Finally, there are 2!=2 ways to arrange the remaining split pair in the other row. This gives a total of 3⋅2⋅2⋅2=24 arrangements for this sub-case.

One Pair Together: There's only one way to choose which pair will sit together. Within that pair, there are 2! ways to arrange them. There are then 2 ways to decide which row the pair sits in, and 3!=6 ways to arrange the remaining two pairs (who must be split) in the other row. This gives a total of 1⋅2⋅2⋅6=24 arrangements for this sub-case.

Adding the sub-cases of Case 2, we get a total of 24+24=48 arrangements.

Total Arrangements

Summing the arrangements from both cases, we get a total of 48(Case1)+48(Case2)=96​ ways to seat the siblings.

Apr 16, 2024
 #1
avatar+174 
0

Analyzing the function:

 

This function defines f(x) as the square root of x minus a nested sequence of square roots that keep getting smaller. Intuitively, as x decreases, the nested square roots will also decrease, bringing f(x) closer to an integer.

 

Finding a bound:

 

For f(x) to be an integer, x - sqrt(x - sqrt(x - ...)) must be a perfect square. Let the innermost square root be y. We can rewrite the function as:

f(x) = sqrt(x - y)

 

Squaring both sides:

 

x - y = f(x)^2

 

Since we want the largest possible three-digit x, let's consider the smallest possible value f(x) can take. The smallest perfect square greater than 10 (a three-digit number) is 121. So, let's assume f(x) = 11.

 

Substituting:

 

x - y = 11^2 = 121

 

This tells us that x needs to be at least 121 more than the innermost square root (y) to be a perfect square.

 

Finding the largest three-digit x:

 

We know x must be greater than 121 + y. Since y is a square root and squares are always non-negative, the largest possible value of y for a three-digit x would be the square root of the largest three-digit perfect square, which is 9^2 = 81.

 

Therefore, x must be greater than 121 + 81 = 202.

 

Checking values:

 

We can now check the largest three-digit perfect squares less than 202:

 

196 (14^2) - When plugged into the function, it results in a non-integer value.

 

169 (13^2) - This value works! f(169) = 13, which is an integer.

 

Therefore, the largest three-digit value of x such that f(x) is an integer is x = 169.

Apr 16, 2024
Apr 15, 2024
 #1
avatar+174 
+1

We can analyze the system of quadratic equations to determine the number of real solutions for different values of c. Here's how:

 

Analyzing the Discriminant:

 

The discriminant of a quadratic equation determines the nature of its roots (solutions). It is denoted by the symbol b2−4ac. In this case, considering the first equation (y = 6x^2 - 9x + c):

 

a = 6

 

b = -9

 

c (variable)

 

The discriminant (d) for the first equation is:

 

d = (-9)^2 - 4 * 6 * c

 

The number of real solutions depends on the value of the discriminant:

 

d > 0: Two real and distinct solutions (roots)

 

d = 0: One repeated real solution (root)

 

d < 0: No real solutions (complex roots)

 

Relating Discriminant to c:

 

We want to find the values of c that correspond to each case.

 

(a) Exactly one real solution:

 

For exactly one real solution (repeated root), the discriminant needs to be zero.

 

Therefore, we need to solve:

 

0 = (-9)^2 - 4 * 6 * c

 

This simplifies to:

 

c = \frac{81}{24} = \dfrac{7}{2}

 

(b) More than one real solution:

 

For more than one real solution (distinct roots), the discriminant needs to be positive.

 

Therefore, we need to solve:

 

0 < (-9)^2 - 4 * 6 * c

 

This simplifies to:

 

c < \dfrac{81}{24} = \dfrac{7}{2}

 

(c) No real solutions:

 

For no real solutions (complex roots), the discriminant needs to be negative.

 

Therefore, we need to solve:

 

0 > (-9)^2 - 4 * 6 * c

 

This simplifies to:

 

c > \dfrac{81}{24} = \dfrac{7}{2}

 

Summary:

 

(a) Exactly one real solution: c = dfrac{7}{2}

 

(b) More than one real solution: c < dfrac{7}{2}

 

(c) No real solutions: c > dfrac{7}{2}

Apr 15, 2024
 #1
avatar+174 
0

We can solve for a and b by utilizing the given information about A and its effect on x and y, along with the property of matrix multiplication.

 

Here's how we proceed:

 

Analyze the equation (A^5)x = ax + by:

 

This equation states that applying matrix A to vector x five times consecutively (A raised to the power of 5) results in a linear combination of x and y, with coefficients a and b.

 

Utilize the information about A:

 

We are given that Ax = y and Ay = x + 2y. These equations define how A transforms x and y.

 

Express (A^5)x in terms of x and y:

 

We can't directly expand (A^5) as it's a high power. However, we can use the given information about A iteratively.

 

Start with the first equation: (A^2)x = A(Ax) = A(y).

 

Substitute from the first given equation: (A^2)x = Ay.

 

Use the second given equation: (A^2)x = x + 2y.

 

Similarly, we can continue:

 

(A^3)x = A((A^2)x) = A(x + 2y) = Ax + 2Ay (using the definition of matrix multiplication).

 

Substitute from the first given equation: (A^3)x = y + 2(x + 2y) = 3x + 4y.

 

We can repeat this process further, but the pattern should be clear.

 

Find an expression for (A^4)x and (A^5)x:

 

Following the established pattern, we can see that:

 

(A^4)x = 3(A^3)x = 3(3x + 4y) = 9x + 12y.

 

(A^5)x = 3(A^4)x = 3(9x + 12y) = 27x + 36y.

 

Substitute (A^5)x in the original equation:

 

The original equation is: (A^5)x = ax + by.

 

Substitute the expression we found for (A^5)x: 27x + 36y = ax + by.

 

Solve for a and b:

 

We want to isolate a and b. Since x and y are not multiples of each other, we can treat them as independent variables.

 

If we set y = 0, the equation becomes 27x = ax, which implies a = 27.

 

If we set x = 0, the equation becomes 36y = by, which implies b = 36.

 

Therefore, in the equation (A^5)x = ax + by, the values of a and b are:

 

a = 27

 

b = 36

Apr 15, 2024

6 Online Users

avatar
avatar
avatar