Question.
Find the point on the x-axis which is equidistant from (2, – 5) and (– 2, 9).
Find the point on the x-axis which is equidistant from (2, – 5) and (– 2, 9).
Solution:
We know that any point on x-axis has its ordinate = 0
Let the required point be P(x, 0).
Let the given points be A(2, –5) and B(–2, 9)
$\therefore \quad \mathrm{AP}=\sqrt{(x-2)^{2}+5^{2}}=\sqrt{x^{2}-4 x+4+25}$
$=\sqrt{x^{2}-4 x+29}$
$\mathrm{BP}=\sqrt{[\mathbf{x}-(-2)]^{2}+(-\mathbf{9})^{2}}=\sqrt{(\mathbf{x}+2)^{2}+(-\mathbf{9})^{2}}$
$=\sqrt{x^{2}+4 x+4+81}=\sqrt{x^{2}+4 x+85}$
Since, $A$ and $B$ are equidistant from $P$,
$\therefore \quad \mathrm{AP}=\mathrm{BP}$
$\Rightarrow \sqrt{x^{2}-4 x+29}=\sqrt{x^{2}+4 x+85}$
$\Rightarrow x^{2}-4 x+29=x^{2}+4 x+85$
$\Rightarrow x^{2}-4 x-x^{2}-4 x=85-29$
$\Rightarrow-8 x=56 \Rightarrow x=\frac{56}{-8}=-7$
$\therefore \quad$ The required point is $(-7,0)$
We know that any point on x-axis has its ordinate = 0
Let the required point be P(x, 0).
Let the given points be A(2, –5) and B(–2, 9)
$\therefore \quad \mathrm{AP}=\sqrt{(x-2)^{2}+5^{2}}=\sqrt{x^{2}-4 x+4+25}$
$=\sqrt{x^{2}-4 x+29}$
$\mathrm{BP}=\sqrt{[\mathbf{x}-(-2)]^{2}+(-\mathbf{9})^{2}}=\sqrt{(\mathbf{x}+2)^{2}+(-\mathbf{9})^{2}}$
$=\sqrt{x^{2}+4 x+4+81}=\sqrt{x^{2}+4 x+85}$
Since, $A$ and $B$ are equidistant from $P$,
$\therefore \quad \mathrm{AP}=\mathrm{BP}$
$\Rightarrow \sqrt{x^{2}-4 x+29}=\sqrt{x^{2}+4 x+85}$
$\Rightarrow x^{2}-4 x+29=x^{2}+4 x+85$
$\Rightarrow x^{2}-4 x-x^{2}-4 x=85-29$
$\Rightarrow-8 x=56 \Rightarrow x=\frac{56}{-8}=-7$
$\therefore \quad$ The required point is $(-7,0)$