Skip to content
🤔prompts chat🧠
🔍
question:Solve the following system of three equations: -21 x-15 y-19 z=18, 15 x-19 y+11 z=-17, -17 y-4 z=20

answer:To solve the system of equations, we can use the method of substitution or elimination. Here, we will use the method of elimination. First, we can eliminate z by adding the second and third equations: (15 x-19 y+11 z)+(-17 y-4 z)=(-17)+20 15 x-36 y+7 z=3 Next, we can eliminate z again by adding the first and third equations: (-21 x-15 y-19 z)+(-17 y-4 z)=18+20 -21 x-32 y-23 z=38 Now, we have two equations with two variables: 15 x-36 y=3 -21 x-32 y=38 We can solve this system of equations using the method of substitution or elimination. Here, we will use the method of substitution. From the first equation, we can express x in terms of y: 15 x=3+36 y x=frac{3+36 y}{15} Substituting this expression for x into the second equation, we get: -21 left(frac{3+36 y}{15}right)-32 y=38 -7+126 y-32 y=38 94 y=45 y=frac{45}{94} Substituting this value of y back into the expression for x, we get: x=frac{3+36 left(frac{45}{94}right)}{15} x=frac{3+180}{15} x=frac{183}{15} Finally, we can substitute the values of x and y into the third equation to solve for z: -17 left(frac{45}{94}right)-4 z=20 -frac{765}{94}-4 z=20 -4 z=20+frac{765}{94} -4 z=frac{1940+765}{94} -4 z=frac{2705}{94} z=-frac{2705}{94 cdot 4} z=-frac{2705}{376} Therefore, the solution to the system of equations is: x=frac{183}{15}, y=frac{45}{94}, z=-frac{2705}{376} The answer is x=frac{13}{2}, y=frac{238}{263}, z=-frac{4653}{526}

question:Determine the critical points of the function {eq}f(x,y) = x^2 - 2x + 6y^2 + 4{/eq} subject to the constraint {eq}(x - 1)^2 + y^2 = 1.{/eq}

answer:Using the Lagrange Multipliers method, we have: begin{align*} nabla f &= lambda nabla g leftlangle {2x - 2,12y} rightrangle &= lambda leftlangle {2left( {x - 1} right),2y} rightrangle end{align*} Solving for x, y, and λ, we get: begin{align*} x &= 1 y &= pm frac{1}{2} lambda &= 6 end{align*} Therefore, the critical points are {eq}(1, frac{1}{2}){/eq} and {eq}(1, -frac{1}{2}).{/eq}

question:There are n+1 boxes, each containing n balls. For every kinleft{ 0,1,ldots,nright} there is exactly 1 box containing k white balls and n-k black balls. A box is picked out and m balls are taken out. Here m<n so the box is not empty yet. All balls that are taken out appear to be white balls. Now another ball is taken out of that same box. What is the probability that it is a white one?

answer:Let there be a box containing n+1 balls. We label the balls with the numbers 1,2,dots,n+1. We take out randomly m+1 balls one by one and denote the drawn numbers by X_{0},X_{1},dots,X_{m}. After drawing the first ball, the balls with a number less than X_{0} are painted white and all other remaining balls are painted black. Then we go on with drawing the other balls. If Y denotes the number of white balls among the balls with labels X_{1},dots,X_{m} then by symmetry it is evident that Y has uniform distribution on left{ 0,1,dots,mright} . Then: Pleft(Y=mright)=frac{1}{m+1} and the event left{ Y=mright} corresponds with the event W_{m} mentioned in the original answer. Therefore, the probability that the next ball drawn is white is frac{m+1}{m+2}.

question:Evaluate the following integral: int_{0}^{2 pi} (128 cos t sin t + 64 cos^2 t) , mathrm{d}t (Give an exact answer, using (pi) as needed.)

answer:begin{split} int_{0}^{2 pi} (128 cos t sin t + 64 cos^2 t) , mathrm{d}t &= 128 int_{0}^{2 pi} cos t sin t , mathrm{d}t + 64 int_{0}^{2 pi} cos^2 t , mathrm{d}t &= 64 int_{0}^{2 pi} sin 2t , mathrm{d}t + 64 int_{0}^{2 pi} frac{1 + cos 2t}{2} , mathrm{d}t &= 64 left[ -frac{1}{2} cos 2t right]_{0}^{2 pi} + 32 left[ t + frac{1}{2} sin 2t right]_{0}^{2 pi} &= 64 left( -frac{1}{2} cos 4pi + frac{1}{2} cos 0 right) + 32 left( 2pi + frac{1}{2} sin 4pi - 0 - frac{1}{2} sin 0 right) &= 64 pi end{split} Therefore, int_{0}^{2 pi} (128 cos t sin t + 64 cos^2 t) , mathrm{d}t = 64 pi

Released under the MIT License.

has loaded