SOLUTION: What is the equation for a line that passes through (6,8) and is perpendicular to 9x+5y=94?

Algebra ->  Graphs -> SOLUTION: What is the equation for a line that passes through (6,8) and is perpendicular to 9x+5y=94?      Log On


   



Question 7792: What is the equation for a line that passes through (6,8) and is perpendicular to 9x+5y=94?
Answer by prince_abubu(198) About Me  (Show Source):
You can put this solution on YOUR website!
They give you the line 9x + 5y = 94, right? If you want to find the slope of the line perpendicular to the line given to you, you must first find the slope of the line given to you.

9x + 5y = 94 needs some work. We need to change that around until we get it to say "y = ".

+9x+%2B+5y+=+94+ <--- start here

+5y+=+94+-+9x+ <--- subtracted 9x from both sides

+y+=+94%2F5+-+%289%2F5%29x+ <---- divide both sides by 5 so that the y can be alone finally. The -9/5 would be the slope of the line given to you.

Now, the slope of the perpendicular is ALWAYS the negative (or opposite) reciprocal. If your slope is -9/5, then the opposite reciprocal will be 5/9. What you do is to flip the fraction and change the sign.

Now, we know that the slope of the perpendicular line will be 5/9. They're given us some additional information. The perpendicular line passes through the point (6,8). There is a formula that exists that we can plug in the slope and a point. That would be +%28y+-+y%5B0%5D%29+=+m%28x+-+x%5B0%5D%29+ where m is your slope, and (x%5B0%5D,y%5B0%5D) is a given point that the line goes through. Let's plug the values in:

+%28y+-+8%29+=+%285%2F9%29%28x+-+6%29+ <--- now this needs some work so that we can put it in standard form

+9%28y+-+8%29+=+5%28x+-+6%29+ <---- multiply the whole equation by 9 to get rid of the fraction.

+9y+-+72+=+5x+-+30+ <---- used distributive property.

+-5x+%2B+9y+=+42+ <---- moved the 5x to the left (as it became -5x) and added 72 to both sides. This is now our equation in standard form. This is the equation of the line perpendicular to 9x+5y=94.