Produsul mezilor e egal cu produsul extremilor .
(4-k) x 5 = 3 x 10
(4-k) x 5 = 30
4-k=30:5
4-k=6
-k=6-4
-k=2
k=-2
sau 4-k=3 x 10 supra 5
4-k=30 supra 5
4-k=6
-k=6-4
-k=2
k=-2
(4-k) x 5 = 3 x 10
(4-k) x 5 = 30
4-k=30:5
4-k=6
-k=6-4
-k=2
k=-2
sau 4-k=3 x 10 supra 5
4-k=30 supra 5
4-k=6
-k=6-4
-k=2
k=-2