Determine the equation of the line which is perpendicular to y = 2x + 9 and crosses through the point (1,2)

When multiplied together the gradients of perpendicular lines should give the answer - 1So: x₁x₂ = -1x₁ = 2 x₂ = -1/2It crosses through the point (1,2)y = ax+ ba = -1/2y = 22 = -1/2 + bb = 5/2so the equation of the line is y = -1/2x + 5/2