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# kombygirl

Questions65
• ### Which laws are supreme - judge-made laws or laws made by parliament?

Which laws are supreme - judge-made laws or laws made by parliament?

1 AnswerLaw & Ethics8 years ago
• ### Factorising...........?

(a) ab - 2a^2b + 3a^2b^10

(b) 16x^2 - 9x^2

• ### Expand and then simplify?

x(x + 3y) - y(3x - y) - (-x^2 + y^2)

• ### Simplifying an equation?

(mx + my) divide (mxy)

• ### simplifing an equation?

I need to simplify (4xy)((3/2)x)/(6x^2y)

that is.. 4xy times 3/2 x divide by 6 x sq y

I've worked it out, but just want to see what other people come up with and how they worked it out to make sure i'm doing it right

• ### Another one on logistics equations?

In ecology, the logistic equation is often written in the form:

dN/dt = rN (1 – N/K),

where N = N(t) stands for the size of the population at time t, the constants r and K stand for the intrinsic growth rate and the carrying capacity of the species, respectively.

If a pond on a fish farm has a carrying capacity of 1000 fish and an intrinsic growth rate of 0.3 (when time is measured in months), and if the pond was originally stocked with 100 fish.

(a) Set up a logistic equation for the fish population N (t) in the pond, with t measured in months.

(b) Find the size of the population when t = 100

(c) Can the population reach 1200 at any future time?

• ### Question on Logistic Equations?

A rabbit population satisfies the logistic equation:

dy/dt = 2 x 10^-7 y (10^6 – y)

where t is the time measured in months. The population is suddenly reduced to 20% of its steady state size by myxamatosis. If the myxamatosis then has no further effect, how large is the population 6 months later? How long will it take for the population to build up again to 90% of its steady state size?

• ### Differential equations?

I've already worked out the following, just need to check I'm doing it right...

Use seperation of variables to solve the following differential equations:

(a) dy/dx = (5-x) / y^2

(b) y^1 = y^2 - (e^3t)(y^2) , y(0) = 1

(c) y^1 + y = 1, y(0) = 2

• ### Differential equations?

Show that the function f(t)=(e^-1 +1)^-1 satisfies y^1+y^2=y and y(0)=1/2

• ### Differential equations?

I've worked this out but not too sure if I've done it right.. Would like to see how others would work it out..

Show that the function f(t) = 3/2et2 - 1/2 is a solution to the differential equation y1 - 2ty = t

• ### Matrices and Vectors?

Assuming that X is a three dimensional vector and:

AX = ( 1 )

( 2 )

( 0 )

Use A^ -1 to find X

• ### Question on Matrices?

Show that A^1 =

(2/3 -1/3 1)

(0 0 1)

(1/6 1/6 -1/2)

• ### Another one on matrix expressions?

Write and evaluate a matrix expression for the average of the two matrices

A [ 216 355 262 ]

[ 453 648 503 ]

B [ 145 338 302 ]

[ 333 624 646 ]

• ### Writing a matrix expression?

Write a matrix expression for the totals of both matrices below:

A [ 216 355 262 ]

[ 453 648 503 ]

B [ 145 338 302 ]

[ 333 624 646 ]

• ### Classification of stationary points?

I've already worked these out, just wanted to check my workings against how other people would work them out...

Find/classify the stationary points of the following functions:

a) z = y sin x

b) z = 2y^2 - xy - 3x

c) z = x^2 - xy + xy^2

• ### Another one on partial derivatives?

Find the partial derivative ∂z / ∂x and ∂z / ∂y of the following function:

z = square root of (x^2 + y^2 +1)

• ### Question on partial derivatives?

Find the partial derivative ∂z / ∂x and ∂z / ∂y of the following function:

z = e^y sin (3x +2)

• ### Area between graphs of two curves?

Calculate the area between the graphs of y = x + 7 and y = x^2 + 1

• ### Area enclosed by a curve and the x-axis?

Find the area enclosed between the curve y=x^3 - 4x^2 and the x-axis