Find the equation of the line passing through the point (2, 2) and cutting off intercepts on the axes, whose sum is 9.
To Find: The equation of the line passing through the point (2, 2) and cutting off intercepts on the axes, whose sum is 9.
Given : Let $\mathrm{a}$ and $\mathrm{b}$ be two intercepts of $\mathrm{x}$-axis and $\mathrm{y}$-axis respectively.
sum of the intercepts is $9, i . e, a+b=9$
$\Rightarrow a=9-b$ or $b=9-a$
Formula used:
The equation of a line is given by:
$\frac{x}{a}+\frac{y}{b}=1$
The given point (2, 2) passing through the line and satisfies the equation of the line.
$\frac{2}{a}+\frac{2}{9-a}=1$
$2(9-a)+2 a=9 a-a^{2}$
$18-2 a+2 a=9 a-a^{2}$
$a^{2}-9 a+18=0$
$a^{2}-6 a-3 a+18=0$
$a(a-6)-3(a-6)=0$
$(a-3)(a-6)=0$
$a=3, a=6$
when $a=3, b=6$ and $a=6, b=3$
case $1:$ when $a=3$ and $b=6$
Equation of the line : $\frac{\mathrm{x}}{\mathrm{a}}+\frac{\mathrm{y}}{\mathrm{b}}=1$
$\frac{x}{3}+\frac{y}{6}$
Hence, 2x + y = 6 is the required equation of the line.
case 2 : when a=6 and b=3
Equation of the line : $\frac{\mathrm{x}}{\mathrm{a}}+\frac{\mathrm{y}}{\mathrm{b}}=1$
$\frac{x}{6}+\frac{y}{3}=1$
Hence , x + 2y = 6 is the required equation of the line.
Therefore, $2 x+y=6$ is the required equation of the line when $a=3$ and $b=6$.And, $x+2 y$ $=6$ is the required equation of the line when $a=6$ and $b=3$.