3. 3. 3. 3. 3. ( )( )b m c n a− − + = −    −    + ⋅ = −    −    + = ⋅ + = + = + =4 2 1 2 3 2 3 4 1 4 2 1 2 1 4 3 5 152 2m n p b+ + = ⋅ + ⋅    ⋅ +    = + + = ⋅ =