Find the equation of the line passing through (1,2) and (3,4).
Correct: A
To find the equation of the line passing through two points, we first find the slope m = (y2 - y1)/(x2 - x1), where (x1,y1) and (x2,y2) are the coordinates of the two points. For the given points (1,2) and (3,4), we have m = (4 - 2)/(3 - 1) = 2/2 = 1. Then using the point-slope form of the equation of a line, y - y1 = m(x - x1), and substituting m = 1 and the point (1,2), we have y - 2 = 1(x - 1). Simplifying gives y - 2 = x - 1, and adding 2 to both sides gives y = x + 1.