Question:
Out of a group of swans, 7/2 times the square root of the total number are playing on the share of a pond. The two remaining ones are swinging in water. Find the total number of swans.
Solution:
Let the total number of swans beĀ x.
Then, total numbers of swans are playing on the share of a pond $=\frac{7}{2} \sqrt{x}$
It is given that
$\frac{7}{2} \sqrt{x}+2=x$
Let $x=y^{2}$, then $\frac{7}{2} y+2=y^{2}$
$\frac{7 y+4}{2}=y^{2}$
$2 y^{2}=7 y+4$
$2 y^{2}-7 y-4=0$
$2 y^{2}+8 y-y-4=0$
$2 y(y+4)-1(y+4)=0$
$(y+4)(2 y-1)=0$
Because $y=\frac{1}{2}$ is not correct.
Thus, $y=-4$ is correct. Putting the value of $y$
$y=-4$
$\sqrt{x}=-4$
Square root both sides, we get
$(\sqrt{x})^{2}=(-4)^{2}$
$x=16$
Therefore, the total number of swans be $x=16$