Question

Find the equation of the line that passes through the points $(3,4)$ and parallel to $x$-axis.

• A. $y=-4$
• B. $y=4$
• C. $4y=3x$
• D. $4y=4x-2$

Answer 1

Answer: (B)

$y=4$

Since any two parallel lines have the same slope we know the slope of the unknown line is $0$ (its from the slope of $y=0\left(x\right)+0$ which is also $0$).

Also since the unknown line goes through $(3,4)$, we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

$y-y_1=m(x-x_1)$ where $m$ is the slope and $(x_1,y_1)$ is the given point.

Now substituting the values:

$y-4=0(x-3)$

$\Rightarrow y-4=0$

$\Rightarrow y=4$

Hence, the equation of the line is $y=4$.