The line l1 l_1\,l1 has gradient 2 and passes through (5,7)(5, 7)(5,7).
Find an equation for l1 l_1\,l1 in the form y=mx+cy = mx + cy=mx+c
l2 l_2\,l2 is perpendicular to l1 l_1\,l1 and passes through (0,1)(0, 1)(0,1)
Find an equation for l2l_2l2.