Thursday

April 24, 2014

April 24, 2014

Total # Posts: 120

**binomial distribution**

hey, i'd really appreciate some help with this question: A medical treatment is successful 75% of the time. A hospital wishes to treat a group of patients. How many patients should they take so that the probablity that all are cured is 1/10? I know that p=0.75 and q=0.25 b...

**maths**

hey, i would really appreciate some help solving for x when: sin2x=cosx Use the identity sin 2A = 2sinAcosA so: sin 2x = cos x 2sinxcosx - cosx = 0 cosx(2sinx - 1)=0 cosx = 0 or 2sinx=1, yielding sinx=1/2 from cosx=0 and by looking at the cosine graph, we conclude that x=pi/2 ...

**maths**

hi, i'm having trouble with this question: The cost of running a train at a constant speed of v km/h is C=50+v^2/1000 dollars/hour find the time taken for an 800km journey in terms of v.

**differentiation**

hey, i'd really appreciate some help differentiating this equation: t= (4+x^2)^(1/2) /3 + (3-x)/5 so that's four plus x to the power of 2 all to the power of 1/2 all over three plus 3-x divided by five... :P Thankyou. I would rewrite it as t= (1/3)(4+x^2)^(1/2) + 3/5 -...

**maximum and minimum problems when function unknown**

Hi, can anyone please help me with this problem, i have no idea what to do! The question is: a window frame is in the shape of a semicircle joined to a rectangle. Find the macimum area of a window using 300 cm of framework. i can usually solve these sorts of questions when i&#...

**equations of tangents and normals**

hi, i'd really appreciate some help solving this question! I am completely at loss here :/ The question is to: Find the equation of the normal to y=loge(x+2) which is parallel to the line with equation y+3x-5=0 I am fine at solving these sorts of equations when they give m...

**circular (trigonometric) functions**

hi, i need help solving this trigonometric equation: sinx+3cosx=0 i don't know what to do as i can't just diviide the two to create tanx which is what i have been doing in previous questions... yes, you are on the right track sinx = -3cosx sinx/cosx = -3 tanx = -3 so x...

**exponential and logarithmic graphs question**

hi, i desperately need help solving this question: Find the values of A and k if the general equation of the graph shown is y=Ae^kx where the graph goes through the points (-1,-4) and (-2,-10) do i solve it using simultaneous equations? because i have attempted this yet failed...

**maths help needed!**

Hi, just a short question. How do i find the x intercepts for the equation y=-2x^3+1 ? I tried to let y equal zero but i could only get as far as x^3=1/2 please help! x^3 = 1/2 is correct. There is only ine x-intercept. It is where x = (1/2)^(1/3) which means the cube root of ...

**Econ T/F**

yes, its a true or false question is this a true or false question? Suppose that after a price change, the income effect is zero, but the substitution effect is not. For such a good, the quantity demanded is directly related to its price. oh well I think it is true. hummmm. Th...

**Econ T/F**

A consumer with a fixed income buys two goods, X and Y. If her demand for both X and Y are unitary elastic, she must spend an equal amount on each good. take a shot, what do you think, and why? i think false, she doesn't have to spend equal amount?? I agree

**Econ T/F**

If a consumer is in equilibrium and all prices and her income increase by 25%, she will consume less of those goods that she considers inferior. if false, explain why. Take a shot. What does your economic reasoning tell you? Hint. If all prices and income rise by exactly 25%, ...

**economics**

According to a survey of U.S. firms, the advertising elasticity of demand is only about 0.003. Does this indicate that firms spend too much on advertising? It does not indicate too much is being spent. A 100% increase in advertising would translate into a .3% increase in sales...

**maths, please help!**

I need help solving this: 6x^2-x-12=0 I usually could do this yet i have completely forgotten what i need to do seeing as there is a number infront of the x^2 This equation is of the general form a x^2 + bx + c = 0 The solution is always x = [-b +/- sqrt (b^2 - 4ac)]/(2a) = [1...

**calculus**

hi, just wondering on how i should approach differentiating: loge1/(3-x)^5 can i differentiate it as loge(3-x)^5? sorry i meant to write (3-x)^-5 Hmmmm. You are haveing a brain seizure. Watch this: Ln x^-a= - ln x^a= -a ln x Amazing. So loge1/(3-x)^5= -5 ln(3-x) Check my think...

**maths**

hi, i would really appreciate some help on simplifying this question: -2(3e^-x-e^x)(-3e^-x-e^x) could this be simplified as -2(3e^-x-e^x)-(3e^-x-e^x) which would then become (-2-1)(3e^-x-e^x) i feel this isn't right however...

**math**

hi i would really appreciate some help solving this question simultaneously: Find A and B such that x-11/(x+3)(2x-1)= A/x+3 + B/2x-1 Multiply both sides by (x+3)(2x-1) to get rid of the fractions. We end up with this: (x-11) = A(2x-1) + B(x+3) You can solve for A and B more ea...

**math**

I need help differentiating this question: 3e^-4x that's three e to the power of negative 4x. when you differentiate, you get: -12e^-4x thanks, but how come it's not -12e^-4x-1, or do i just not minus a one when the power is a co-efficient? Remember, the differential o...

**acids and alkalis**

TOOTH PASTE - Alkali OVE CLEANER - Alkali Soz nufin else maybe some more in a minute!!! gtg Bye XXX

**Geometry?**

I need help with these: Suppose triangleABC ~ triangleJKL with BC = 28, JK = 12, and KL = 42. Find the perimeter of triangleABC if the perimeter of triangleJKL is 72. & Find the scale factor of triangleDEF to triangleXYZ if triangleDEF ~ triangleXYZ, DE=10, XZ=20, and XY=45. I...