Question

What is the equation of a line that contains the point (2,1) and is perpendicular to the line: y = 3x – 4?

Answer 1

Y = 3x - 4.....the slope here is 3. A perpendicular line will have a negative reciprocal slope. To find the negative reciprocal, u flip the slope and change the sign. So we will need a slope of -1/3...see how I flipped the slope of 3/1 and made it 1/3...and then changed the sign, making it -1/3.

y = mx + b
slope(m) = -1/3
(2,1)...x = 2 and y = 1
now we sub and find b, the y int
1 = -1/3(2) + b
1 = -2/3 + b
1 + 2/3 = b
3/3 + 2/3 = b
5/3 = b

so ur perpendicular equation is : y = -1/3x + 5/3