Question

What is an equation of the line that passes through the points (1, 2) and (2, -1)?

Answer 1

slope(m) = y2 -y1/ x2 - x1

m = -1 - 2/ 2 - 1

m = -3/1 ; m = -3

using the formula y -y1 = m(x - x1)

y - 2 = -3( x -1)

y -2 = -3x +3

collect like terms

3 +2 = y + 3x

y + 3x = 5

y = -3x + 5( y = mx + c)

equation of the line= y = -3x + 5