| written 9.5 years ago by |
Consider the first eq i.e
$qxy = 4$ i.e $qx = 4/y$
Let $x = 0$ then $y = \infty$
There $(0, \infty )$
Let $x = \infty$ then $y = 0$
$( \infty , 0)$
When $ x = 1, y = 4/q$
When $y = 1, x = 4/q$
Plotting through diagram
We get,

Now consider 2nd equation
i.e $2x + y = z --------- (2)$
Let $x = 0 y = 2$
Let $y = 0 x = 1$
Equation (2) is a straight line passing from $(0, 2)$ and $(1, 0)$
This line is intersecting curve at solving eq (2)
$Xy = 4/9, x = 4/9y$

Substituting value of x in eq (2)
$\therefore y=\dfrac 43 $ & $\dfrac 23$
Corresponding x is
$x=\dfrac 4{9\times \dfrac43}=\dfrac 13$
$x=\dfrac 4{9\times \dfrac43}=\dfrac 23$
Hence the points of intersection of the hyperbola and the line are $(2/3, 2/3)$ and $(1/3, 4/3)$
Now considering the horizontal strip which will slide along x axis i.e from $1/3$ to $22/3 $ which is outer limit.
Upper limit is equation of line $2x + y = 2$ in terms of y we get $y = 2 – 2x$
Lower limit is equation of curves
$qxy = 4$ in terms of y
we get $y = 4/qx$
$A=\int\limits_{1/3}^{2/3}\int\limits_{4/9x}^{2-2x} dydx$
Integrating w.r.t y we get
$A=\int\limits_{1/3}^{2/3}[y]^{2-2x}_{4/9x}dx$
$A=\int\limits_{1/3}^{2/3}2-2x-\dfrac 4{9x}dx$
$A=\Bigg[2x-\dfrac {2x^2}2-\dfrac 49\log x\Bigg]^{2/3}_{1/3}$
$A=\dfrac 43-\dfrac 49-\dfrac 49\log 2/3$
$=-\dfrac 23+\dfrac 19+\dfrac 49\log 1/3$
$=\dfrac 13-\dfrac 49\Big[\log 2-\log 3-\log 1+\log 3\Big]$
$=\dfrac 13 -\dfrac 49\log 2$

and 2 others joined a min ago.