Answer:
Length = 27 metres
Width = 9 metres
Step-by-step explanation:
Consider the width to be x.
Then the length will be 3x.
The perimeter is 66m when the width is increased by 1m and the length is decreased by 4m.
So the dimensions will become:
Length=3x-4
Width=x+1
Now solve for the variable x using the formula for perimeter of a rectangle:
P = 2(l+b)
66 = 2(3x-4+x+1) (Divide both sides by 2 and simplify the parentheses)
33 = 4x-3 (Add 3 to both sides)
36 = 4x (Divide both sides by 4)
x = 9
Now plug-in the value of x into the original dimensions which were:
Length=3x
Width=x
So the dimensions are:
Length = 27 metres
Width = 9 metres
a circle with a diameter of 2cm has a circumference of 6.28 cm
Dy/dx = y/(x^2)
dy/y = dx/(x^2)
int[dy/y] = int[dx/(x^2)] ... apply integral to both sides
ln(|y|) = (-1/x) + C
|y| = e^{(-1/x) + C}
|y| = e^C*e^(-1/x)
|y| = C*e^(-1/x)
y = C*e^(-1/x)
So you have the correct answer. Nice job.
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Check:
y = C*e^(-1/x)
dy/dx = d/dx[C*e^(-1/x)]
dy/dx = d/dx[-1/x]*C*e^(-1/x)
dy/dx = (1/(x^2))*C*e^(-1/x)
is the expression for the left hand side (LHS)
y/(x^2) = [C*e^(-1/x)]/(x^2)
y/(x^2) = (1/(x^2))*C*e^(-1/x)
is the expression for the right hand side (RHS)
Since LHS = RHS, this confirms the solution for dy/dx = y/(x^2)
Isn't it already telling you how much each oz of detergent is?
