AboutAbe Mantell Expertise Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!
Experience Over 15 years teaching at the college level.
Organizations belong to NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.
Education/Credentials B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook
Question How do I find the equation of a line that is perpendicular to another line with equation x-3y=5 and passes through the point (4,13)
Answer Hello Belle,
Rewrite x-3y=5 as -3y=-x+5 then y=(1/3)x-5/3, so the slope is 1/3.
Since perpendicular lines have slopes that are negative reciprocals
of each other, the perpendicular line has a slope of -3.
Now find the equation of the line with slope -3 through the point (4,13).
==> y-13=-3(x-4) ==> y-13=-3x+12 ==> y=-3x+25
