If p+q+r = 1 and pq+qr+pr = - 1, and pqr = - 1, find the value of

Pq+qr+pr = pqr (because they are both equal to - 1)

then you divide both sides by p to get

q + qr/p + r = qr. then you divide both sides by q and get

r/p + r/q = r. so I divided both sides by r to get

P + q = 0 therefore p = - q. putting that into the first equation allows you to get that r=1 because p and q cancel each other out. then I put that into pq+qr+pr=-1 so pq+q+p=-1 since p=-q the q+p gets canceled out and you're left with pq=-1 and since it is the product of the two numbers and q is the negative of p. q=-1 while p=1. therefore p=1 r=1 and q=-1