Given \[ 2x - y + 2z = 2, \quad x - 2y + z = -4, \quad x + y + \lambda z = 4, \] then the value of \( \lambda \) such that the given system of equations has no solution is:
If the roots of the quadratic equation \( ax^2 + bx + c = 0 \) are real and equal, then: