Question

8 years ago, my mother's age was 4 times my age 9 years from now. What will be linear equation in two variable? Also find slope of that equation.

• A. $y=4x+44$ where $y$ is my mother's present age and $x$ is my present age.
• B. Slope $=4$
• C. $4y=x+44$ where $y$ is my mother's present age and $x$ is my present age.
• D. slope$=3$

Answer 1

Answer: (A), (B)

Slope $=4$

Let present age of my mother be $y$ and that of mine is $x$.
$8$ years ago means age of mother's be $(y-8)$
and $9$ years later my age means $(x+9)$
According to question
$y-8=4(x+9)$
$\Rightarrow y=8+4x+36$
$\Rightarrow y=4x+44$
This is the required equation.

On comparing with slope-intercept form of line $y=mx+b$ where $m$ is slope of the line and $b$ is y-intercept of the line.
Slope $=4$