SOLUTION: Find the equation, in standard form, with all integer coefficients, of the line perpendicular to x + 3y = 12 and passing through (9, -5). I normally do not ask for help, but I

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Question 104002: Find the equation, in standard form, with all integer coefficients, of the line perpendicular to x + 3y = 12 and passing through (9, -5).

I normally do not ask for help, but I am lost on this problem. If anyone can help, I would greatly appreciate it.

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

First convert the standard equation into slope intercept form

Solved by pluggable solver: Converting Linear Equations in Standard form to Slope-Intercept Form (and vice versa)
Convert from standard form (Ax+By = C) to slope-intercept form (y = mx+b)


Start with the given equation


Subtract 1x from both sides


Simplify


Divide both sides by 3 to isolate y


Break up the fraction on the right hand side


Reduce and simplify


The original equation (standard form) is equivalent to (slope-intercept form)


The equation is in the form where is the slope and is the y intercept.







Now let's find the equation of the line that is perpendicular to which goes through (9,-5)

Solved by pluggable solver: Finding the Equation of a Line Parallel or Perpendicular to a Given Line


Remember, any two perpendicular lines are negative reciprocals of each other. So if you're given the slope of , you can find the perpendicular slope by this formula:

where is the perpendicular slope


So plug in the given slope to find the perpendicular slope



When you divide fractions, you multiply the first fraction (which is really ) by the reciprocal of the second



Multiply the fractions.


So the perpendicular slope is



So now we know the slope of the unknown line is (its the negative reciprocal of from the line ). Also since the unknown line goes through (9,-5), we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

where m is the slope and (,) is the given point



Plug in , , and



Distribute



Multiply



Subtract from both sides to isolate y

Combine like terms

So the equation of the line that is perpendicular to and goes through (,) is


So here are the graphs of the equations and




graph of the given equation (red) and graph of the line (green) that is perpendicular to the given graph and goes through (,)





Now convert into standard form


Solved by pluggable solver: Converting Linear Equations in Standard form to Slope-Intercept Form (and vice versa)
Convert from slope-intercept form (y = mx+b) to standard form (Ax+By = C)


Start with the given equation


Subtract 3x from both sides


Simplify


Multiply both sides by -1 to make the A coefficient positive (note: this step may be optional; it will depend on your teacher and/or textbook)


Distribute and simplify


The original equation (slope-intercept form) is equivalent to (standard form where A > 0)


The equation is in the form where , and






So the equation of the line that is perpendicular to x + 3y = 12 and passing through (9, -5) is



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