Find the equation of the line that is perpendicular to 2x-9y=-3 and also goes through the point (-1, 2). Write the answer in slope intercept form

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ANSWER

[tex]y=-\frac{9}{2}x-\frac{5}{2}[/tex]

EXPLANATION

Two lines are perpendicular if their slopes are opposite reciprocals of each other.

In this case, we can rewrite the equation of the given line in slope-intercept form by solving the equation for y,

[tex]2x-9y=-3[/tex]

Add 9y to both sides,

[tex]\begin{gathered} 2x-9y+9y=-3+9y \\ 2x=-3+9y \end{gathered}[/tex]

Add 3 to both sides,

[tex]2x+3=9y[/tex]

And divide both sides by 9,

[tex]y=\frac{2}{9}x+\frac{3}{9}[/tex]

As we can see, the slope of the given line is 2/9. Its opposite reciprocal is -9/2. This is the slope of the line we have to find,

[tex]y=-\frac{9}{2}x+b[/tex]

To find the y-intercept, b, we have to use the point (-1, 2). Replace x and y with the coordinates of the point,

[tex]2=-\frac{9}{2}(-1)+b[/tex]

And solve for b,

[tex]\begin{gathered} 2=\frac{9}{2}+b \\ \\ 2-\frac{9}{2}=b \\ \\ \frac{4-9}{2}=b \\ \\ -\frac{5}{2}=b \end{gathered}[/tex]

Hence, the equation of the line is,

[tex]y=-\frac{9}{2}x-\frac{5}{2}[/tex]