Question 98·Medium·Algebra

If one line has slope $m$, a perpendicular line has slope $-\frac{1}{m}$ (negative reciprocal).

With slope $m$ and point $(x_1,y_1)$, start from $y-y_1=m(x-x_1)$.

After you get an equation, rewrite it into the same form as the choices (often $Ax+By=C$).

Enter $2x-y=5$ and add the point $A=(3,-1)$.

Since the guideline has slope $2$, enter the perpendicular line through $A$:

Rewrite the line you graphed into standard form and select the answer choice that matches it.

Rewrite $2x-y=5$ in slope-intercept form:

So the slope of the guideline is $2$.

A line perpendicular to slope $2$ has slope $-\frac{1}{2}$.

Use point-slope form with point $(3,-1)$:

Subtract 1 from both sides:

Multiply by 2:

So the correct choice is $x + 2y = 1$.