Question

If two points $P=(0,–1)$ and $Q=(4,1)$ are on a straight line, find equation of the Straight line.

• A. $y=\frac{1}{2}x-1$
• B. $y=3x-1$
• C. $y=2x-2$
• D. $y=2x-1$

Answer 1

The correct option is A $y=\frac{1}{2}x-1$

Slope$=\frac{(y_2-y_1)}{(x_2-x_1)}=\frac{1}{2}=m$
Substitute $m=\frac{1}{2}$, into the equation, $y=mx+b$,
to get the equation $y=\frac{1}{2}x+b$
Select one of the given points, for example $(4,1)$, and substitute the $x$ and $y$ values into the equation $y=\frac{1}{2}x+b$
We, then, get that $b=-1,$ which is the y-intercept.
Substitute $b=-1$ to get the equation.
$y=\frac{1}{2}x-1$