Question

Find the equation of the line passing through the points (1, 8) and (2, 7)

• A. $x-y-9=0$
• B. $x+y+9=0$
• C. $x+y-9=0$
• D. $2x+y+9=0$

Answer 1

The correct option is C $x+y-9=0$

Given: Points (1, 8) and (2, 7)

We know that the slope of the line passing through the points $(x_1,y_1)$ and $(x_2,y_2)$ is $\frac{y_2-y_1}{x_2-x_1}$.
So, slope of the line(m) = $\frac{7-8}{2-1}$
Slope of the line(m) = -1

Equation of the line: $y-y_1=m(x-x_1)$
Equation of the line: $y-8=-1(x-1)$
Equation of the line: $y-8=-x+1$
Equation of the line: $x+y-9=0$