# Posts by deel

Total # Posts: 21

**math**

please help me how to solve the integral sinx/x dx from 0 to infinite : ∫_0^∞▒〖sinx/x dx〗 thank you

*March 24, 2013*

**linear algebra**

in order to grow a certain crop, it is recommended that each square foot of ground be treated with 10 units of phosphorous, 9 units of potassium, and 19 units of nitrogen, suppose that there are three brands of fertilizer on the market - say brand X, brand Y, and brand Z. One ...

*November 11, 2012*

**math**

please help me to solve this assignment : consider a 2D mirror has a parabolic profile of y = (x-3)^2 + 5 facing toward y^+ direction. Prove that any beam of light in y^- direction that this hits the mirror will be reflected toward a particular point (i.e. known as the focus ...

*September 18, 2012*

**math**

consider a 2D mirror has a parabolic profile of y = (x-3)^2 + 5 facing toward y^+ direction. Prove that any beam of light in y^- direction that this hits the mirror will be reflected toward a particular point (i.e. known as the focus of parabolic mirror.

*September 17, 2012*

**math**

find the derivatives, dy/dx for the folowing function : y=ln(cos(0.5)+(sin(x^2+3))^1/3)

*August 25, 2012*

**math**

how to find the following limit : lim lnx/lgx x->infinity

*August 21, 2012*

**math**

thank's steve :)

*August 20, 2012*

**math**

yes i'm sure..the assignment like that.

*August 20, 2012*

**math**

find the derivatives, dy/dx, for the following functions : y=(1+sin^2{2 exp (3x)})^5y please help me to solve this assignment. thank's

*August 20, 2012*

**math**

Please help me to find an equation for the tangent to the curve xsin2y=ycos2x at the point (phi/4, phi/2)

*August 13, 2012*

**math**

A right circular cylinder of radius r and height h is inscribed in a right circular cone of radius R and height H, as shown on the right figure. Find the value of r (in terms of R and H) that maximizes the total surface area of the cylinder (including top and bottom). Comment ...

*August 11, 2012*

**math**

thanks for your help :)

*August 10, 2012*

**math**

y(t)=amount of alcohol in the tank at time t dy/dt =y’(t) = alcohol inflow rate – alcohol outflow rate = 4 - 5(y/50) =200 - 5y/50 = 5 (40-y)/50 dy/dt = 5 (40-y)/50 Separate variable and integrate : dy/(40-y) = 5/50dt -ln(40-y) = 0.1t + C ln(40-y) = -0...

*August 10, 2012*

**math**

oke thanks, i'ill try it

*August 10, 2012*

**math**

A tank contains 50 gallons of a solution composed of 90% water and 10% alcohol. A second solution containing 50% water and 50% alcohol is added to the tank at rate of 4 gallons per minute. As the second solution is being added, the tank is being drained at the rate of 5 ...

*August 10, 2012*

**math**

yes i understand now, thanks for your help

*August 9, 2012*

**math**

h^3=s/kw h^3=s/k(12-h) sorry, I'm still confused how to get the function of h. please help me to complete the assignment. thank you

*August 9, 2012*

**math**

The stiffness S of a rectangular beam is proportional to its width (w) times the cube of its depth/height (h). find the dimensions (i.e.: w and h) of stiffest beam that can be cut from a log which has a circular cross-section with diameter of 12-in.

*August 9, 2012*

**math**

thanks for your help

*August 8, 2012*

**math**

In a room of 20.000 ft^3 of air, 600 ft^3 of fresh air flows in per minute, and the mixture (made practically inform by circulating fans) is exhausted at a rate of 600 cubic feet per minute (cfm). What is the amount of fresh air inside the room y(t) at any time, if y(0)=0? ...

*August 8, 2012*

**math**

thanks for your help

*August 8, 2012*

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