If p : q : r = (y - z) : (z - x) : (x - y), then the value of px + qy + rz is
Since p : q : r = (y - z) : (z - x) : (x – y),
let p = k(y – z)
q = k(z – x)
r = k(x – y)
px + qr + rz = kx(y - z) + ky(z - x) + kz(x – y) = k(xy – xz + yz – xy + xz – yz) = k(0) = 0.
Therefore, the value of px + qy + rz = 0.