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❓The quadratic (x^2 - 6x + 5 = 2x - 11) needs to be solved for (x). What is the sum of the solutions?
💡Okay, so I have this quadratic equation to solve: (x^2 - 6x + 5 = 2x - 11). Hmm, I remember that to solve a quadratic equation, I need to get everything on one side so that it equals zero. Let me try to do that first.Alright, so I'll subtract (2x) and add (11) to both sides to move those terms to the left. That should give me:(x^2 - 6x + 5 - 2x + 11 = 0)Wait, let me double-check that. Subtracting (2x) from both sides would be (x^2 - 6x - 2x + 5 + 11 = 0). Yeah, that looks right. Now, combining like terms:-6x minus 2x is -8x, and 5 plus 11 is 16. So the equation simplifies to:(x^2 - 8x + 16 = 0)Hmm, this looks familiar. I think this might be a perfect square trinomial. Let me see if it fits the form ((x - a)^2). Expanding ((x - a)^2) gives (x^2 - 2ax + a^2). Comparing that to my equation, (x^2 - 8x + 16), I can set up the following:-2a should equal -8, so a would be 4.And (a^2) should equal 16, which it does because 4 squared is 16.So, that means my equation can be written as:((x - 4)^2 = 0)Now, to solve for x, I take the square root of both sides. The square root of ((x - 4)^2) is (x - 4), and the square root of 0 is 0. So:(x - 4 = 0)Adding 4 to both sides gives:(x = 4)Wait a second, so does that mean the equation has only one solution? It seems like it's a repeated root because the quadratic is a perfect square. So, even though it's a quadratic equation, it only has one unique solution, but it's repeated twice.But the question asks for the sum of the solutions. If there's only one solution, but it's repeated, does that mean I count it twice? I think so, because in the quadratic equation, the sum of the roots is given by (-b/a), where the equation is in the form (ax^2 + bx + c = 0). In my case, (a = 1), (b = -8), so the sum should be (-(-8)/1 = 8). Let me verify that. If the equation is ((x - 4)^2 = 0), then both roots are 4, so adding them together gives 4 + 4 = 8. Yeah, that makes sense. So even though it's a repeated root, the sum is still 8.I guess another way to think about it is that the quadratic equation can have two roots, even if they're the same. So, in this case, both roots are 4, and their sum is 8. That aligns with the formula I remembered earlier.So, to recap, I moved all terms to one side, simplified the equation, recognized it as a perfect square, solved for x, and then calculated the sum of the solutions. Everything checks out, and the sum is 8.
❓Two cards are dealt at random from a collection of two standard decks of cards (104 cards total). What is the probability that the first card is a heartsuit and the second card is an ace?
💡First, I need to determine the total number of cards in the collection. Since there are two standard decks, that makes a total of 104 cards.Next, I'll calculate the probability of drawing a heart as the first card. There are 26 hearts in each deck, so with two decks, there are 52 hearts. Therefore, the probability of drawing a heart first is 52 out of 104, which simplifies to 1/2.After drawing a heart, there are now 103 cards left in the collection. I need to find the probability of drawing an ace next. There are 8 aces in total (4 from each deck). However, if the first heart drawn was the ace of hearts, then there are only 7 aces left. If the first heart was not an ace, there are still 8 aces remaining.I'll consider two scenarios:1. The first card is the ace of hearts.2. The first card is a heart but not an ace.For the first scenario, the probability of drawing the ace of hearts first is 2 out of 104, which simplifies to 1/52. Then, the probability of drawing one of the remaining 7 aces is 7 out of 103. Multiplying these probabilities gives (1/52) * (7/103) = 7/5356.For the second scenario, the probability of drawing a heart that is not an ace is 24 out of 104, which simplifies to 3/13. Then, the probability of drawing an ace from the remaining 8 aces is 8 out of 103. Multiplying these probabilities gives (3/13) * (8/103) = 24/1339.Finally, I'll add the probabilities of both scenarios to find the total probability:7/5356 + 24/1339 = 7/5356 + 96/5356 = 103/5356 = 1/52.So, the probability that the first card is a heart and the second card is an ace is 1/52.
❓Which of the following conclusions is incorrect?A: "x∈N" is a sufficient but not necessary condition for "x∈Q"B: "∃x∈N*, x^2-3<0" is a false propositionC: In triangle ABC, with sides a, b, c opposite to angles A, B, C respectively, the equation "a^2+b^2=c^2" is a necessary and sufficient condition for "triangle ABC is a right triangle"D: The negation of the proposition "∀x>0, x^2-3>0" is "∃x>0, x^2-3≤0"
💡Alright, so I've got this multiple-choice question here, and I need to figure out which of the conclusions is incorrect. There are four options: A, B, C, and D. Let me go through each one step by step.Starting with option A: "x∈N" is a sufficient but not necessary condition for "x∈Q". Okay, so N stands for natural numbers, and Q stands for rational numbers. I know that all natural numbers are rational because you can express any natural number as a fraction where the denominator is 1. So, if x is a natural number, it's definitely a rational number. That makes "x∈N" a sufficient condition for "x∈Q". But is it necessary? Well, no, because there are rational numbers that are not natural numbers, like fractions or negative numbers. So, "x∈N" isn't necessary for "x∈Q". Therefore, option A seems correct.Moving on to option B: "∃x∈N*, x^2 - 3 < 0" is a false proposition. N* usually refers to the set of positive natural numbers, which are 1, 2, 3, and so on. Let's test this proposition. If x is 1, then 1^2 - 3 = 1 - 3 = -2, which is less than 0. So, there exists at least one x in N* that satisfies the inequality. That means the proposition is actually true, not false. So, option B is incorrect because it claims the proposition is false when it's actually true.Next is option C: In triangle ABC, with sides a, b, c opposite to angles A, B, C respectively, the equation "a^2 + b^2 = c^2" is a necessary and sufficient condition for "triangle ABC is a right triangle". Hmm, this is referring to the Pythagorean theorem. I remember that if a triangle satisfies a^2 + b^2 = c^2, then it's a right triangle with the right angle opposite side c. Conversely, if a triangle is a right triangle, then this equation holds. So, the condition is both necessary and sufficient. However, the option says it's a necessary and sufficient condition, which seems correct. Wait, no, the option says it's a necessary and sufficient condition, but I think it's only a sufficient condition because the sides could be arranged differently. No, actually, in any right triangle, the sum of the squares of the two shorter sides equals the square of the longest side. So, if a^2 + b^2 = c^2, then c must be the hypotenuse, making it a right triangle. And if it's a right triangle, then this equation must hold. So, it's both necessary and sufficient. Therefore, option C is correct.Finally, option D: The negation of the proposition "∀x>0, x^2 - 3 > 0" is "∃x>0, x^2 - 3 ≤ 0". Let's recall how to negate statements with quantifiers. The negation of "for all x, P(x)" is "there exists x such that not P(x)". So, the negation of "∀x>0, x^2 - 3 > 0" should be "∃x>0, x^2 - 3 ≤ 0". That matches what's given in option D. Therefore, option D is correct.Wait, but earlier I thought option C was correct, but now I'm second-guessing myself. Let me double-check. The equation a^2 + b^2 = c^2 is indeed the condition for a right triangle. If a triangle is right-angled, then this equation holds, and if this equation holds, then the triangle is right-angled. So, it's both necessary and sufficient. Therefore, option C is correct.So, going back, the only incorrect conclusion is option B because it incorrectly states that the proposition is false when it's actually true.
❓A fourteen-sided figure, composed using 1 text{ cm}times 1 text{ cm} grid squares, is constructed as shown below. What is the area of the figure in text{cm}^2?[asy] unitsize(8mm); for (int i=0; i<8; ++i) { draw((i,0)--(i,8),gray); draw((0,i+1)--(8,i+1),gray); } draw((1,4)--(2,5)--(2,6)--(3,7)--(4,6)--(5,6)--(6,5)--(7,4)--(6,3)--(6,2)--(5,1)--(4,2)--(3,2)--(2,3)--cycle,black+2bp); [/asy]textbf{(A) } 15 qquad textbf{(B) } 15.5 qquad textbf{(C) } 16 qquad textbf{(D) } 16.5 qquad textbf{(E) } 17
💡To determine the area of the fourteen-sided figure, we can use the following steps:1. **Identify the Coordinates**: The figure is drawn on a grid, and the coordinates of the vertices are given. By listing these coordinates, we can better visualize and calculate the area.2. **Apply the Shoelace Formula**: This formula is useful for finding the area of a polygon when the coordinates of its vertices are known. The formula is: [ text{Area} = frac{1}{2} left| sum_{i=1}^{n} (x_i y_{i+1} - x_{i+1} y_i) right| ] where ( (x_{n+1}, y_{n+1}) = (x_1, y_1) ).3. **Calculate the Summations**: Plug the coordinates into the formula and compute the necessary summations.4. **Compute the Area**: After calculating the summations, apply the formula to find the area.5. **Verify the Result**: Ensure that the calculations are correct and that the area makes sense given the figure's structure.By following these steps, we can accurately determine the area of the figure.
❓A 25 cm wide path is to be made around a circular garden having a diameter of 4 meters. What is the approximate area of the path in square meters?
💡First, I need to determine the radius of the circular garden. Given that the diameter is 4 meters, the radius is half of that, which is 2 meters.Next, the path around the garden is 25 cm wide, which is 0.25 meters. To find the radius of the larger circle that includes the garden and the path, I add the width of the path to the radius of the garden:2 meters + 0.25 meters = 2.25 meters.Now, I calculate the area of the larger circle using the formula for the area of a circle, ( A = pi r^2 ):( A_{text{large}} = pi times (2.25)^2 = pi times 5.0625 ).Similarly, I calculate the area of the smaller circle (the garden itself):( A_{text{small}} = pi times (2)^2 = pi times 4 ).To find the area of the path, I subtract the area of the smaller circle from the area of the larger circle:( A_{text{path}} = A_{text{large}} - A_{text{small}} = 5.0625pi - 4pi = 1.0625pi ).Finally, using the approximation ( pi approx 3.1416 ), I calculate the numerical value:( A_{text{path}} approx 1.0625 times 3.1416 approx 3.34 ) square meters.
❓Determine the smallest positive period of the function y=3tan ( frac {x}{2}+ frac {π}{3}).
💡Okay, so I need to find the smallest positive period of the function y = 3 tan(x/2 + π/3). Hmm, I remember that the period of a tangent function is related to how often it repeats its pattern. The basic tangent function, y = tan(x), has a period of π because it repeats every π units. But when there are transformations applied, like stretching or shifting, the period can change.In this function, there's a coefficient in front of x inside the tangent function, which is 1/2. I think this affects the period. Maybe it stretches or compresses the graph. I recall that for functions like y = tan(Bx + C), the period is π divided by the absolute value of B. So, if B is greater than 1, the period is smaller, meaning the graph is compressed. If B is between 0 and 1, the period is larger, meaning the graph is stretched.Let me write that down: Period = π / |B|. In this case, B is 1/2, so the period should be π divided by 1/2, which is the same as π multiplied by 2, so 2π. Wait, but I also remember that sometimes the formula is given as 2π / |B| for some trigonometric functions. Is that correct?Hold on, maybe I confused it with sine or cosine functions. For sine and cosine, the period is 2π / |B|, but for tangent, it's π / |B|. Let me double-check that. Yes, tangent has a period of π, so when you have a coefficient B inside, it's π / |B|. So, in this case, B is 1/2, so the period is π / (1/2) = 2π.Wait, but the function also has a vertical stretch by a factor of 3 and a phase shift of π/3. Does that affect the period? I don't think so because the period is about how often the function repeats, not about how high or low it goes or where it starts. So, the vertical stretch and phase shift shouldn't change the period.So, putting it all together, the period of y = 3 tan(x/2 + π/3) is 2π. Let me just visualize it to make sure. If I compare it to the basic tan(x), which repeats every π, this one is stretched by a factor of 2, so it should repeat every 2π. That makes sense because the x is being divided by 2, which stretches the graph horizontally.I think I'm confident now. The smallest positive period is 2π.