A straight line, LLL, has equation y=−12x+9\displaystyle y = -\frac{1}{2}x + 9y=−21x+9. The straight line perpendicular to L L\,L passes through the point with coordinates (4,7)(4, 7)(4,7).
Find an equation of the straight line perpendicular to LLL.
130 exam-style questions on Eduqas GCSE Maths Perpendicular Lines and the equation of a tangent. Each one has a worked solution and a mark scheme showing where the marks go.