Question

The graphs of the two linear equations ax + by = c and bx - ay = c, where a, b and c are all not equal to zero,

A. are parallel
B. intersect at one point but not perpendicular
C. intersect at two points
D. perpendicular

Answer 1

im pretty sure it would be d

Answer 2

let us find the slopes of the two lines

a x + b y = c , slope m1 = - a / b

b x - a y = c , slope m2 = b / a

m1*m2 = (- a / b)(b / a) = - 1

The two lines are perpendicular