# Posts by enigma

Total # Posts: 15

**math**

(-1,1) is classified as a saddle point because the value it gives after the second derivative test is less than 0 therefore the value is inconclusive. While (0,1) is classified as a local maximum because the value it gives after the second derivative test is a negative.

*September 26, 2012*

**math**

i apologise if that is the case. it's just that i have no idea where to start. thank you for your time.

*September 26, 2012*

**math**

A function is given by, f(x,y) = x^4 - y^2 - 2x^2 + 2y - 7 Using the second derivative test for functions of two variables, classify the points (0,1) and (-1,1) as local maximum, local minimum or inconclusive.

*September 26, 2012*

**math**

thanks for helping me. i was stuck trying to solve this.

*September 26, 2012*

**math**

A function of two variables is given by, f (x,y) = 4x^3 + 7xy^4 - 5y^2 + 8 Determine, fxx + fyx at x = 4.25 and y = 3.69, giving your answer to 3 decimal places.

*September 26, 2012*

**math**

A function of two variables is given by, f(x,y) = e^2x-3y Find the tangent approximation to f(0.989,1.166) near (0,0), giving your answer to 4 decimal places.

*September 26, 2012*

**math**

A function of three variables is given by, f (x,y,t) = x3y2sin t + 4x2t + 5yt2 + 4xycos t Find ft (3.44,0.58,8.1) giving your answer to 3 decimal places.

*September 26, 2012*

**math**

after re-calculating the euler-midpoint method. the value I got was 1.8172 while using normal euler method is 1.968. however, I can't seem to find the exact solution to minus off the 1.8172 value to get the global error.

*September 26, 2012*

**math**

after calculating the y' and y'' values. the values come up be 2.7731947639 which when rounded to 5 decimal places gives the answer as: 2.773195

*September 26, 2012*

**math**

An initial-value problem is given by the differential equation, f(x,y) = x + y, y(0) = 1.64 The Euler-midpoint method is used to find an approximate value to y(0.1) with a step size of h = 0.1. Then use the integrating factor method, to find the exact value of y(0.1). Hence, ...

*September 26, 2012*

**math**

Consider the initial value problem, f(x,y) = y(18.06 - y), y(0) = 12. The exact solution of the problem increases from y(0) =12 to y = 18.06 as x increases without limit. Determine the minimum upper bound of h for the classical 4th-order Runge Kutta method to be absolutely ...

*September 26, 2012*

**math**

An initial-value problem is given by the differential equation, f(x,y)=x(1-y^2), y(1)=0.07 Use the Euler-trapezoidal method with a step-size h = 0.1, to obtain the approximate value of y(1.1). Give your answer to 4 decimal places.

*September 26, 2012*

**math**

An initial-value problem is given by the differential equation, f(x,y)=-20xy^2, y(1)=1. Use the classical fourth-order Runge-Kutta method with a step-size of h=0.02, to obtain the approximate value of y(1.02). Give your answer to 6 decimal places.

*September 26, 2012*

**math**

i was going around in circles and putting the wrong values. thank you for your help. thanks.

*September 26, 2012*

**math**

A function is given by, f(x)=e^-3x write down the third-order Taylor approximation for f(x) about x =0. Hence, evaluate f(0.258) giving your answer to 4 decimal places.

*September 26, 2012*

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